Teacher Notes on All Description-Writing Exercises

Exercise G: Guidelines used in the other exercises

Context for this case: Other versions: Plain, printable for students. Comparable guidelines for writing instructions. Introduce these guidelines by "touring" them with CDC's Sudden Unexplained Infant Death reporting form.   Cognitive Apprenticeship Features: "Reveals the magic" behind effective technical descriptions. Connects writing to authentic, nonschool reader needs.

Guidelines for Writing Good Descriptions Organization OVERVIEW. Begin with a brief overview that reveals the object's (a) overall framework, arrangement, or shape, and (b) purpose or function. PARTS. Divide the object into parts and describe each part (a) in enough detail to use, make, or draw it, and (b) in a way that reveals its role, its relation to other parts. ORDER. Organize the part descriptions to help your reader: (a) spatial order (top to bottom, outside to inside), or (b) priority order (most to least important), or (c) chronological order (order of [dis]assembly). Content SPECIFICS. Include relevant specific features (such as size, shape, color, material, technical names). Omit irrelevant background, confusing details, and needless words. COMPARISON. Compare features or parts with other things already familiar. CONTRAST. Contrast properties with different ones to reveal their significance. Signals for Your Reader FORMAT. Clarify your text with: Heads. Identify topics with clear, nested section headings. Lists. Itemize related features with indenting and marks. Figures. Integrate figures and text with labels and references. VERBAL CUES. Guide your reader's expectations with: Parallelism. Use parallel words and phrases for parallel ideas. Proleptics. Use verbal links (also, but, however, etc.) to signal how your description fits together.

Three Roles for These Guidelines

1. Audience analysis.
   The guidelines introduce the importance of writing for and helping an audience that depends on what you say. This concept will be new to many students, who expect to write only for their teacher. Reviewing the guidelines points out that technical texts (including descriptions of technically complex things) have real readers, and that those readers need the writer's help to understand the thing described.
2. Writing for a Purpose.
   While students can quickly see that people write and read instructions to help them carry out a (complex) task, they may need help seeing why people write and read carefully crafted technical descriptions.

   A. The Tour.
   One way to reveal the purpose of good descriptions is to tour the description-writing guidelines and give a brief, concrete example of each principle applied. Pointing out the different result of honoring or ignoring each principle, one by one with a simple case, shows just how well-designed descriptions are useful in ways that poor descriptions are not. See the "Giving a Guideline Tour" section below for an easy, systematic way to do this with a "crime scene" flavor that interests students.

   B. The Trial Run.
   A second approach may work better for younger students or those for whom discussing so many guidelines at once proves too abstract. Start instead with Exercise 0. Post the overt four-item "why write descriptions" list from the annotated version of that exercise and then have students try that simple description practice themselves. Afterwards, backtrack from the overt four-reasons list and from the writing problems that turn up during Exercise 0 to introduce each guideline as a solution to a common problem that all description writers face. With this list of potential solutions at hand, students can then apply them to the draft description in the paper clip case (Exercise 1) and to subsequent exercises.

3. Repair Techniques.
   The guidelines provide students with an overt, shared repertoire of techniques for repairing the flaws that they find in descriptions (from themselves or from others). The guidelines offer goals to strive for in good descriptions, and ways to improve weak descriptive passages. Finally, the guidelines are a kind of loaned experience: they make explicit for beginners what working professional writers and scientists know implicitly through long practice (thus they promote cognitive apprenticeship).

Giving a Guideline Tour

An easy, focused way to introduce each of these guidelines to students is to "tour" through them using some authentic technical descriptions to illustrate how they work. Sudden unexplained infant death (SUID) is a practical situation where real-life reporting (description) forms are not only available to the public but eagerly shared to promote their wider use. Hence, I have found that SUID forms from the U.S. Centers for Disease Control and Prevention (freely posted at
http://www.cdc.gov/mmwr/PDF/rr/rr4510.pdf )
provide a dramatic way to introduce the good-description guidelines to otherwise disinterested high-school students.

The six-page SUID "investigation report form" at the above URL contains many clever descriptive features. First, it includes a concrete example of virtually every technique listed on the basic guidelines for good descriptions above. Surveying the SUID form is a convenient, persuasive way to highlight those techniques.

Second, the SUID form is heavily scaffolded (with checklists, labeled tables to fill in, and prompted comparisons). Yet this exposure of often-hidden descriptive moves is very much "for life," not just for school. At the sometimes chaotic death scene, first responders who witness possibly crucial details (about temperature, ventilation, or clothing, for example) need clear, organized prompts to help them record diverse nutritional, medical, and environmental clues in reliable ways. Months later and thousands of miles away (at CDC in Atlanta), investigators need systematic, easily compared reports rich enough in detail to suggest possible causes. The scaffolding on the SUID form helps both groups meet their needs in complementary ways. This is also a keen lesson for students in the social value of good technical description, for writers and readers alike.

Third, CDC's SUID form includes front and side infant-body outlines on which paramedics can mark wounds or scars. Many technical descriptions blend words and pictures, so this offers a practical introduction to the general design challenges of effective text-graphics integration.

Finally, this real-life SUID form has its share of little imperfections that students can be asked to find and improve by using the guidelines (it needs a better way than a small empty box, for instance, to capture information about prescription and OTC medications that the infant was taking). So it affords a nice opportunity to explore the benefits of guideline-based text revision. The CSI flavor of this technical description case makes it appealing; the usability features make it a very helpful instructional tool.

Comparison with Darlene Smith-Worthington

Several items in the guidelines here overlap with those that Darlene Smith-Worthington includes in her Technical Communication: Writing Descriptions (Perfection Learning, 1997, 32 pp.), a short high-school technical writing text. Smith-Worthington approaches description writing quite broadly. She spends time on general audience analysis, on "observing things," and on literary terminology (simile contrasted with metaphor and analogy, for example). Her guidelines for writing and revising descriptions are helpful, but they appear only late in her text (pp. 16 and 24, the last half of the book). Several extended example descriptions treat familiar but mechanically complex objects (a rotary egg beater, a clothes hanger) and could support much more commentary than they receive. One strength of her book is her use of nutrition labels and similar tabular product specifications, which she cleverly contrasts with descriptions in sentence and paragraph format.

My approach to teaching technical description places greater stress than Smith-Worthington does on the psychological and linguistic techniques that make good descriptions good. I follow the same empirical, research-based approach to teaching technical writing that the American Federation of Teachers promotes for effectively teaching reading (summarized in Louisa C. Moats, Teaching Reading IS Rocket Science, Washington, D.C.: American Federation of Teachers, 1999, 32 pp., available free online). The last 30 years have revealed much about the psychological grounds for nonfiction text usability; we should not ignore these discoveries when introducing students to effective drafting and revising techniques. The exercises here embody this work, and the guidelines (especially the "Signals for Your Reader" section at the end) make them explicit (since seeing them spelled out and naming them help new students recognize them in action).

I also introduce description-writing guidelines before, not after, the exercises to which they apply. And I suggest explicitly invoking them in every subsequent lesson. They tie the separate exercises together: an easy way to review at the start of each lesson, an overt focus for practice, and a shared evaluation standard. I have even hung these guidelines in the classroom as a 3-by-4-foot poster to provide visual continuity and a tangible resource for student writers.

Guideline Commentary by Patricia Wright

Exercise 0: The fist on the card

(C) Discover things.
If you haven't "toured" the CDC's 6-page reporting form (at http://www.cdc.gov/mmwr/PDF/rr/rr4510.pdf) for sudden unexplained infant death (SUID) when introducing students to the good-description guidelines, this is he place to explore its features. Discovering what causes SUID requires rich (detailed) descriptions of many infant deaths by many people in many places. But this much information would be useless to CDC epidemiologists trying to discover trends, causal patterns, and prevention strategies unless it was very carefully organized and labeled, presented in a way that allows easy comparison and invites thoughtful review. The SUID reporting form features (as mentioned in the annotation for the description guidelines) promote just such analysis and discovery.

(D) Understand things.
Making, installing, and discovering things usually involve understanding them better, of course. But sometimes better understanding is itself the prime purpose of a detailed technical description.
(i) Every prescription drug comes with a "package insert," for example, a sheet of fine-print elaborate descriptions of its biological effects, side effects, and known interactions with other drugs. This legal document both promotes appropriate use of the drug and limits the liability of the drug maker if problems arise.
(ii) Understanding can have great practical value even with no theoretical basis. Garbage bills from the Waste Management trash service are quite complex. The bill's many fields can easily confuse ESL readers or anyone with weak reading skills. So Waste Management distributes (and posts online at http://www.wmorangecounty.com/images/HowToReadComm.pdf) a two-page explanatory descriptive chart keyed to each part of the bill, which attempts (with mixed results; you can critique them with your students) to reveal "What means what?" for those who do not understand.

(2) OFFER THE CHALLENGE:

(A) Prepare the target.
Get a package of 3-by-5-inch nonwhite index cards and a rubber stamp with a pointing index finger (called by printers a "fist"). Stamp each card with the pointing finger, identically. Alternatively, use the pointing finger image file displayed here

and a package of colored paper to print or copy bookmark-shaped paper strips each with the "fist" image on one end.

(B) Distribute.
Give each student a nonwhite card or paper strip with the very specific directional "fist" imprint on one end.

(C) Invite Description.
Tell the students to imagine the entire contents of their classroom jumbled into a pile of debris by an earthquake or tornado. Suppose that recovering from the rubble that one specifically marked card (or strip) now in their hand was crucial (for solving a crime or rescuing missing people, for example). How could they describe in words that unique physical thing so that searchers could reliably find it (and distinguish it from all other debris) amid the jumbled classroom contents? Students can write their descriptive phrases or sentences directly on the card (or strip) itself to reinforce their focus on its relevant features. (For a more structured activity, see item (4) below.)

(3) BUILD ON THE RESULTS:

(A) Look (briefly) at what the students generally chose to write and to omit when trying to describe their card for recovery. Acknowledging their effort while noting descriptive trends that would hinder searchers makes everyone aware of the nontrivial nature of useful technical description. For example, I have found that many students describe the "fist" with
(i) a purely subjective direction ("points to the girl next to me" instead of "points to the right if held at the top of the card facing the viewer"), or
(ii) a spurious interpretation ("points accusatorily"), while others
(iii) omit highly relevant details (the card or paper is not white, a very helpful clue for finding it amid most classroom paper that is white).

(B) If time permits, have students exchange cards with a neighbor and comment on the differences between their own description and that of the other student. This shows that intuitions are seldom enough; one needs systematic techniques to describe something reliably for others.

(4) CONTRAST CLASS--A SCAFFOLDED ALTERNATIVE:
If your students would benefit from a more structured, scaffolded approach to this exercise, introduce them to contrast classes as a technique for discovering what to include in a useful description.

(A) Definition.
A contrast class is a set of alternative things or reference items from which a case is drawn and to which it is then compared. For instance, a "jumbo shrimp" is large compared to other shrimp (contrast class A), but small compared to lobsters (class B) or marine mammals (class C). Contrast classes are important for computing conditional probabilities and in informal logic. They also reveal which details are relevant to making a proposed description useful for its audience.

(B) Comparison chart.
You can evaluate (or help students self-evaluate) the fist-on-the-card draft descriptions with the help of a simple chart that progressively discloses different possible (increasingly narrow) contrast classes (left column) and focuses student attention on which features of the card (hence, which descriptive details) distinguish this unusual object from each contrast class in turn:

     Contrast class          Relevant distinguishing feature(s)
     [how is sought item     Most class            This sought
     different from...?]     members               item
     -------------------     -------               -----
     furniture in room       metal, wood           paper

     classroom paper
          color              white                 blue
          size               8.5-by-11 in.         3-by-5 in.

     other 3-by-5 cards      plain                 "fist" image

     other marked cards      other image shapes    fist shape,
                                                   orientation

(C) Usability connection.
Considering contrast classes is not only a descriptive technique that students can practice, but it also offers a concrete approach to audience analysis. Different audiences in different circumstances may expect a description to work "against" different contrast classes, so a responsible writer tries to anticipate such audience needs to make their text as usable as they can. (In this case, only an audience of rubble searchers that needed to distinguish the sought card from many others marked almost identically would need the most specific details in the right column of the chart above.)

Case:

Student version/annotated version:
This exercise has no draft text to focus student activity (that's why it is "Exercise 0"). Students generate the text based on the properties of the marked card before them. Everyone who writes such technical descriptions always faces these challenges in meeting the needs of their audience:
(1) The problem of relevant completeness.
Readers need ample detail (here, the specific color and shape of the card would greatly help retrieve it) without irrelevant distractions (what the fist "points to," which varies for everyone who holds it).
(2) The problem of meaningful detail.
One of the most revealing parts of most technical descriptions is the purpose of the item(s) described (as the guidelines point out), because this often explains or shows the importance of the other descriptive details. (Although the marked card does not really have a purpose, the subsequent exercises do illustrate this feature.)
(3) The problem of effective delivery.
Since no sequence of steps "naturally" organizes a description the way it organizes a set of instructions, extra signals within the text to guide the reader are especially important. Good description writers must carefully construct these signals, and a lack of them is a common omission in student descriptions of the marked card. (Exercise 1 pursues this point.)

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
[no reading in this exercise]
Writing:
Grade 5--"...develop [a] topic with simple facts, details, examples, and explanations" (p. 31).
Grade 9/10--"Make distinctions between the relative value and significance of specific data, facts, and ideas" (p. 60).

Exercise 1: The paper clip

(3) TARGET TEXT:
The student version of the paper clip description ("description case 1" below) contains the target text in the left column, divided by sentence (or very short paragraph), with scaffolding prompts (for key description features and their roles) in the right column. This lets you introduce a simple explicit technical description and focus student attention on what each part of the text contributes to the description's success (how each part helps the reader).
 
(4) SIGNAL HUNT:
To make an early, active connection between the description-writing guidelines and this sample description text, I ask students to read the text carefully and circle every reader signal that they find. Reading any text carefully enough (and more than once) so that they notice individual reader signals is a novel process for many students (and especially helpful for ESL students) . They must pay attention to the (last third of the) guidelines and to the role that specific text phrases play, and your commentary can help them recognize that a good description contains many signals installed by the writer just to help the reader follow and understand the text better. Among the most obvious here are the many labeled references to Figure 1 as well as the list of loops (first, second, third...) with parallel phrases for parallel physical parts.
 
(5) ROLE RECOGNITION:
With this signal recognition as a warm up, I then turn attention to the other description features. Confident students can write down their response to each prompt (right side) and then compare answers. Many students will need overt modelling of this general feature-recognition process, however. You might find it more helpful to distribute the fully annotated version of Exercise 1 rather than the student version (with prompts only) and then tour the exposed answers, discussing the contribution of each identified feature to the usability of the overall description. This shows more concrete cases of the description-writing guidelines in action. And it again reinforces the idea that in a good description no part of the text is idle; every part works:

• This is indispensable ground work for the realization that the writer is responsible for making every part work.
• This is a natural way to acquaint students with the idea that when they write descriptions, making every part work (for their readers) falls on them.
• Role-recognition exercises like this also build up each student's general cognitive maturity so they can learn well from other examples by spontaneously "self-explaining" what each feature of the example contributes.
• Together, activities (4) and (5) "reveal the magic" behind building an effective description: it is never just a jumble of technical terms, but rather a carefully crafted web of specific reader-support features.

Case:

Student version:

Description Case 1:  Paper Clip

     Description

A "Gem-style" paper clip is a            FEATURE:
length of stiff steel wire bent
into three flat, nested loops            WHY:
(Fig. 1) to hold sheets of paper
together when they are inserted
between the loops.

The wire is a 1-mm-diameter
steel cylinder that is 10 cm             FEATURE:
long.  It is bendable in the             WHY:
fingers but stiff.

The first loop (a) is a smooth,
U-shaped turn to the right
that starts 2 cm from the
outermost end of the wire.

The second loop (b) is a                 FEATURE:
U-shaped turn to the left                WHY:
that starts 3 cm farther
along the wire and has a                 FEATURE:
diameter just small enough               WHY:
to fit snugly within the
first loop.

The third loop (c) is another
U-shaped turn to the right
that starts 2 cm beyond (b)
and has a diameter just small
enough to fit snugly within
the second loop (as well as
the first).

The wire in each inner loop              FEATURE:
touches and runs parallel to             WHY:
the outer loop that wraps
around it.  All three loops
lie in the same plane, and
pushing them out of that
plane just enough to slide
several sheets of paper
between them makes the paper             FEATURE:
clip act like a spring and               WHY:
squeeze the sheets together.

Annotated version:

Description Case 1:  Paper Clip (Annotated)

     Description                                  Analysis

A "Gem-style" paper clip is a            FEATURE: Overview
length of stiff steel wire bent
into three flat, nested loops            WHY: (1) show framework
(Fig. 1) to hold sheets of paper
together when they are inserted               (2) show purpose
between the loops.

The wire is a 1-mm-diameter
steel cylinder that is 10 cm             FEATURE: contrast (implicit)
long.  It is bendable in the             WHY: reveal design decisions
fingers but stiff.                            (1) vs. ribbon or braided wire

The first loop (a) is a smooth,
U-shaped turn to the right                    (2) vs.  V-shaped turn
that starts 2 cm from the
outermost end of the wire.

The second loop (b) is a                 FEATURE: order (spatial)
U-shaped turn to the left                WHY: easy to follow
that starts 3 cm farther
along the wire and has a                 FEATURE: specifics
diameter just small enough               WHY: show relations among parts
to fit snugly within the
first loop.

The third loop (c) is another
U-shaped turn to the right
that starts 2 cm beyond (b)
and has a diameter just small
enough to fit snugly within
the second loop (as well as
the first).

The wire in each inner loop              FEATURE: specifics
touches and runs parallel to             WHY: show relations among parts
the outer loop that wraps
around it.  All three loops
lie in the same plane, and
pushing them out of that
plane just enough to slide
several sheets of paper
between them makes the paper             FEATURE: comparison
clip act like a spring and               WHY: reveal role of parts
squeeze the sheets together.

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
Grade 5--"Understand how text features make information accessible and usable" (p. 28).
Grade 7--"Understand and explain the use of a simple mechanical device..." (p. 43).
Grade 11/12--"Analyze both the features and the rhetorical devices of...public documents" (p. 66).
Writing:
Grade 8--"Write technical documents...use formatting techniques to aid comprehension" (p. 51).

Exercise 2: Nail clippers

(D) Drawn art.
Students may wonder why anyone would draw nail clippers, as Macaulay has done here, when one could simply photograph them to illustrate a technical description. While the realism of photographs has its place (in sales catalogs, for example), technical drawing actually helps readers more than photography in many learning situations.
(i) First, the artist can control the perspective and "lighting" of the illustrated object more completely than in most photographs.
(ii) Second, the artist can intentionally omit irrelevant details that clutter and confuse many photographs of complex objects.
(iii) Finally, by choice of line and color, the technical illustrator can focus the reader's attention on the most important parts and how they interact, often showing contact or motion that would remain obscure, perhaps even invisible, in most photographs. So good technical artists follow much the same guidelines as do good technical writers, only implemented visually rather than in words.
(Another very authentic case that demonstrates the benefits to readers of drawn technical art rather than photographs is Home Improvement 1-2-3, published by Meredith Books Group for the Home Depot hardware chain. This 475-page reference book contains hundreds of illustrated procedures for household projects (such as "installing a bathtub" on p. 127). Yet the picture of the authors inside the front cover is one of the few photographs in the entire book, because drawn color illustrations (sampled on the book's cover) show the situations, tools, and activities much more usefully, for the three reasons listed above.)

(E) Relevance signals.
Macaulay's personal style focuses reader attention by drawing important features realistically (often with exaggerated clarity) while drawing unimportant features of the same object whimsically. The cartoonlike aspects of his diagrams are those details the reader can and should gloss over (he signals); the accurately drawn aspects are those to dwell on and study. For example, how the finger approaches the nail-clipper blades and how the nail trimmings are removed are unimportant details here, so Macaulay uses whimsical little cartoon men to signal visually that those features are the ones not to take seriously in his nail clippers diagram.

TEXT ANALYSIS:
The text for Exercise 2 is a basic but thorough description of nail clippers, integrated with the two-part illustration of nail clippers on p. 23 of Macaulay's The New Way Things Work.

(A) Student version.
The student version presents the descriptive text in short paragraphs (left column), with prompts for key features and their roles (right column). Working through the sample description slowly, and spelling out what each part contributes to the description's adequacy (based on the description-writing guidelines) reminds students that good descriptions have no stray parts: everything in the text helps the reader in some way.

(B)Annotated version.
The annotated version of the nail clippers description presents the same text but overtly identifies each (scaffolded) feature (using guideline terms) and its rhetorical role. Macaulay's large, realistic line drawing of nail clippers (cited in the text as "Fig. 1") is the basis for the spatial organization of the third, fourth, and fifth paragraphs. Macaulay's smaller, labeled schematic drawing of the levers that comprise the clippers (cited in the text as "Fig. 2") shows how a different kind of art can support explanatory comparisons that greatly increase the description's value for its readers.

(C) More.
Students can do more with this exercise than just identify the descriptive features and what each contributes. After you review the sample text (below), see the Extended Activity section for extra student activities that I have used with this description.

Case:

Student version:

Description Case 2:  Nail Clippers

     Description                                  Analysis

Nail clippers combine two steel          FEATURE:
levers to make a strong, stable          WHY:
tool that clips off the end of a
finger nail with little applied
force and much control.

Clippers consist of three steel          FEATURE:
strips about 1 cm wide, 5 cm             WHY:
long, and 1 mm thick.
A steel post (3 mm in diameter
and 1 cm long) connects all
these strips (Fig. 1).
The bottom strip is riveted
to the post at right angles;
the other two strips fit over
the post through a circular
hole in each that lets them
move freely along its length.
                                         FEATURE:
The top strip forms the handle           WHY:
of the clippers.  It bends
upward at a 45-degree angle
about one fifth of the way
from the end that passes over
the post, against which the
the handle's short end pivots.

The bottom strip is straight,            FEATURE:
with a short 90-degree bend and          WHY:
beveled cutting edge on the end
nearest the post.

The middle strip gently
bends upward about 10 degrees
near the end away from the post.
It is welded at that end to the
bottom strip (below it).
At the other end, which is free
to move, it has a short vertical
section (bent toward the lower
strip),  also with a beveled
cutting edge.

The handle (top strip) forms a           FEATURE:
second-class lever, with its             WHY:
fulcrum at the post (F in
Fig. 2).  Gentle force moves
the long end through a long
distance, applying high force
(at the bend) to the middle
of the strip below it.

The middle strip forms a                 FEATURE(S):
third-class lever, with its
fulcrum (F) at the welded                WHY:
end.  High force applied to
its middle by the handle bend
(above it) moves the cutting
edge gently through enough
distance to meet the facing
edge below it, carefully
cutting any finger nail
inserted between the beveled
edges.

Annotated version:

Description Case 2:  Nail Clippers (Annotated)

     Description                                  Analysis

Nail clippers combine two steel          FEATURE: overview
levers to make a strong, stable          WHY: show purpose
tool that clips off the end of a
finger nail with little applied
force and much control.

Clippers consist of three steel          FEATURE: parts
strips about 1 cm wide, 5 cm             WHY: show relations
long, and 1 mm thick.
A steel post (3 mm in diameter
and 1 cm long) connects all
these strips (Fig. 1).
The bottom strip is riveted
to the post at right angles;
the other two strips fit over
the post through a circular
hole in each that lets them
move freely along its length.
                                         FEATURE: order (spatial,
The top strip forms the handle                    outside to inside)
of the clippers.  It bends               WHY: show relations
upward at a 45-degree angle
about one fifth of the way
from the end that passes over
the post, against which the
the handle's short end pivots.

The bottom strip is straight,            FEATURE: specifics
with a short 90-degree bend and          WHY: relevant details
beveled cutting edge on the end
nearest the post.

The middle strip gently
bends upward about 10 degrees
near the end away from the post.
It is welded at that end to the
bottom strip (below it).
At the other end, which is free
to move, it has a short vertical
section (bent toward the lower
strip),  also with a beveled
cutting edge.

The handle (top strip) forms a           FEATURE: comparison
second-class lever, with its             WHY: show role
fulcrum at the post (F in
Fig. 2).  Gentle force moves
the long end through a long
distance, applying high force
(at the bend) to the middle
of the strip below it.

The middle strip forms a                 FEATURE(S): comparison
third-class lever, with its                          and contrast
fulcrum (F) at the welded                WHY: show different role
end.  High force applied to
its middle by the handle bend
(above it) moves the cutting
edge gently through enough
distance to meet the facing
edge below it, carefully
cutting any finger nail
inserted between the beveled
edges.

Extended Activities:

All of these extra activities focus student attention on how the writer "signals the reader" to help them follow and understand the text. This teaches students how to read more carefully themselves (by attending to such text signals) and how to deploy similar signals when they too write descriptions.

(A) Order signals.
The order (see guidelines, first part) of this description is spatial (outside to inside, a "path" that Macaulay's drawing greatly assists).

• How does the writer signal this organization to the reader? Students should discover the sequence signals "top," "bottom," and "middle" in the third, fourth, and fifth paragraphs.
• How else could this be done? The writer could have added part labels (A, B, C) to the three metal strips and then mentioned those labels overtly in the text to tie a paragraph to each part pictured (a common practice). Students could carry out this improvement.

(B) Figure integration.
Even without part labels, the description text does link to each figure.

• Where? (paragraphs 2 and 6).
• How? (callouts "Fig. 1" and "Fig. 2"). Note that these figures look different and serve very different purposes.
• How else? (each figure could have a short caption that suggested its intended role).

(C) Pronouns.
Pronouns are a more subtle signal, a trail of proleptics by which the writer lays down a thread of continuity for the reader to follow through the description.

• How many times does "it" or "its" occur in this description? (10 times).
• Why?
  (a) To easily say more about the same thing.
  (b) To remind the reader of the current topic (by pointing back to it).
  (c) To keep the text shorter (by not repeating each referenced phrase).

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
Grade 5--"Understand how text features make information accessible and usable" (p. 28).
Grade 7--"Understand and explain the use of a simple mechanical device..." (p. 43).
Grade 11/12--"Analyze both the features and the rhetorical devices of...public documents" (p. 66).
Writing:
Grade 8--"Write technical documents...use formatting techniques to aid comprehension" (p. 51).

Exercise 3: The Compact Disk (CD)

HOW TO USE THIS EXERCISE:

(A) (Optional) Role Recognition.
You can use Exercise 3 for more practice in recognizing the features of a description and their roles, if you wish. Below I provide a student version with text (left column) and feature prompts (right column), which you can pair with the fully annotated version to drill role recognition (as with Exercises 1 and 2). I prefer to use this exercise for text reconstruction, however (next).

(B) Text Reconstruction (Background).
In On the Surface of Discourse (London: George Allen and Unwin, 1983), text linguist Michael Hoey reports (pp. 3-6) how he and E. O. Winter found that 55% of 229 computer science, chemistry, and engineering students "demonstrated beyond dispute an ability to reconstruct a [technical] discourse out of a jumble of sentences" by attending to text features and continuity signals installed by the author. The 11% of students who failed completely at this were all ESL learners.
Furthermore, reconstructing a description from fragments is a surprisingly "authentic" technical writing exercise. I point out to my students that at work I often receive (many) separate parts of a future description, perhaps at different times from different people. Like the students with Exercise 3, I have to build a useful, coherent large description by paying careful attention to what each fragment says and how it complements the other fragments. (The student fragments are known to be a complete set and previously edited, of course, while on the job the description fragments are often incomplete and need much editorial improvement.)

(C) Text Reconstruction (Process).
Below I provide a "segmented" version of the student CD description. It has the same text (without the scaffolding) as before, but marks (---) divide it into 14 (roughly) paragraph-sized chunks. The descriptive chunks omit the headings, which appear in a separate list for you to use as the project outline. But the text chunks are large enough to each contain several signals or rhetorical clues about each chunk's intended role in and contribution to the overall description.

• Print out
  the segmented version of the CD description and cut it into pieces (of paper) along the marks (---) indicated.
• Enlarge
  each text chunk on a photocopy machine for easier in-class reading and sharing. Everyone can participate more easily if the description parts (that you assemble as puzzle pieces on the wall) have print big enough to read from across the room. Alternatively, use less enlargement and reassemble the description on a big table.
• Scramble
  the text pieces so that their original order is hidden.
• Distribute
  the (enlarged) text chunks randomly, one to each student (or perhaps to each pair of students).
• Read each piece aloud
  and try to find its best place. Use its internal rhetorical features (as mentioned on the guidelines) as clues and the list of headings and the figures as an organizing "target" framework, a broad outline of the intended result. Student discussion may perform most of this work in some classes; you will need to provide considerable leadership and encouragement in others since this is valuable but unfamiliar territory for many students. In some cases, even reading their text chunk aloud for classmates to consider may challenge the student who holds it.
• Post
  each text chunk on a wall or blackboard (with little pieces of tape or Post-it notes) as students decide on its preliminary role and place. But don't tape the paper sheets to each other unless you can easily undo them, because changing the order and grouping is a natural and appropriate part of reconstructing the whole description from its parts.
• Adapt
  the growing description as new pieces of the puzzle are read and reviewed. As in real life, first guesses may need to be revised to accommodate later arriving chunks of text that clarify the overall structure of the description that you are (re)building.
• Review
  the emerging whole as the last pieces fall into place, as you would with any puzzle. This approach enables students, cooperatively, to "write" a long, complex technical description using important, real-world design principles (the guidelines), without having to compose each separate piece of prose. It shows "actively" how the pieces of a good description have features that knit together to form a coherent pattern intended to help readers use the text well. Since the students must focus on those same text features to rebuild the description, they come to see why writers bother to deploy them.

Case:

Student version [headings only, for outline]:

Description Case 3:  Compact Disk



Overview


General Shape

     Size

     Capacity

The Layers


The Groove

     One-track Design

     Moving the Groove

The Pits


The Optical Read-Out System

Student version [with scaffolding]:

Description Case 3:  Compact Disk

     Description                                  Analysis

Overview

A compact disk (CD), like a              FEATURE:
phonograph record, stores                WHY:
information physically for
electronic replay, and, like a
phonograph record, it stores the
information along a single spiral
groove on the side of a plastic
circle.

In contrast to a phonograph              FEATURE:
record, however, a CD                    WHY:
  * stores the information in
    digital (on/off) rather than
    analog (variable shape) form,
    and
  * is read by reflected (laser)
    light, rather than by vibrating
    a needle that travels along the
    groove.

General Shape

     Size
A compact disk is a circle of            FEATURE:
clear plastic (polycarbonate)            WHY:
about 12 cm in diameter and
1 mm thick, with a 1.5-cm
diameter hole in the center.
CDs are stamped from a mold that
leaves a spiral track lined with
pits (little dents) on the CD's
bottom side (details below),
while the top side is smooth.

     Capacity
The surface area of a CD is just         FEATURE:
less than twice (1.77 times) as          WHY:
large as the surface area of a
3.5-inch magnetic "floppy" disk.
But because the pits store
information much more densely
than the iron oxide particles on
a floppy disk, a CD holds at
least 350 times more data (at
least 500 Mbyte on a CD, only
1.44 Mbyte a magnetic disk).

The Layers                               FEATURE:
                                         WHY:
CDs consist of three layers (see
Fig. 1):
(a) The bottom layer is the              FEATURE:
    stamped, grooved plastic.            WHY:
(b) Above that lies a very thin
    film of aluminum (or chrome-
    aluminum alloy).   This
    metallic film reflects any           FEATURE:
    light entering the disk from         WHY:
    below, except where the pits
    fall in the plastic layer.

(c) Above the reflective metal
    layer is a coat of acrylic
    lacquer that protects the
    metal from scratches and
    oxidation.  It also allows
    printing descriptive labels
    safely on the top side of
    the disk.

The Groove

     One-track Design
The groove on the bottom surface
of a CD is a single channel that
spirals outward from the center
to the edge.  This track is              FEATURE:
thinner than a human hair and            WHY:
several kilometers long.
(The spiral differs from the             FEATURE:
many concentric rings of iron            WHY:
oxide (see Fig. 2) that store
information on a magnetic disk.)

     Moving the Groove
The spindle through a CD's center
hole (see Fig. 3, d) connects
the disk to a variable-speed             FEATURE:
motor (unlike the constant-speed         WHY:
motor on a phonograph turntable).

The disk turns (clockwise) about
500 revolutions/minute (e) when          FEATURE:
the reading laser beam is at the         WHY:
center, but only about 200
revolutions/minute when the beam
reaches the outer edge.
This causes the track to pass
over the read-out system (f),
which gradually moves from the
center to the edge, at a
constant linear speed, to help
reliably detect the pits.

The Pits

The moving spiral track is lined         FEATURE:
with pits (dents) and flat spots         WHY:
("lands").  These vary in size
and placement in a sequence that
represents the information stored.
The pit sequence can digitally           FEATURE:
encode text, images, computer            WHY:
programs, or the left- and right-
hand audio signals of a stereo
sound recording.

Additional pits
  * give location and timing
    information (for player
    display), and
  * control the motor speed
    so that the reading rate
    remains constant.

The Optical Read-Out System

Two lenses and a semi-transparent        FEATURE:
(partially silvered) mirror              WHY:
(see Fig. 4) direct the laser
beam from below at the track on
the spinning CD.

If the laser beam strikes a pit          FEATURE:
on the track (g), it is not              WHY:
reflected.  The light-sensitive
photodiode (detector) below the
mirror sees no beam and produces
no signal.
If the laser beam strikes a land
between pits on the track (h),
it reflects back straight through
the mirror to the photodiode
below.  This detector then
produces an electric signal.

For compatibility with other
electronic equipment, a special
reversing circuit (a "not gate")
then turns these pit
interruptions into ON signals
(binary 1s) and turns the land
reflections into OFF signals
(binary 0s).

Student version [segmented, no scaffolding]:

Description Case 3:  Compact Disk

                                       ---
A compact disk (CD), like a
phonograph record, stores
information physically for
electronic replay, and, like a
phonograph record, it stores the
information along a single spiral
groove on the side of a plastic
circle.
                                       ---
In contrast to a phonograph
record, however, a CD
  * stores the information in
    digital (on/off) rather than
    analog (variable shape) form,
    and
  * is read by reflected (laser)
    light, rather than by vibrating
    a needle that travels along the
    groove.
                                       ---
A compact disk is a circle of
clear plastic (polycarbonate)
about 12 cm in diameter and
1 mm thick, with a 1.5-cm
diameter hole in the center.
CDs are stamped from a mold that
leaves a spiral track lined with
pits (little dents) on the CD's
bottom side (details below),
while the top side is smooth.
                                       ---
The surface area of a CD is just
less than twice (1.77 times) as
large as the surface area of a
3.5-inch magnetic "floppy" disk.
But because the pits store
information much more densely
than the iron oxide particles on
a floppy disk, a CD holds at
least 350 times more data (at
least 500 Mbyte on a CD, only
1.44 Mbyte a magnetic disk).
                                       ---
CDs consist of three layers (see
Fig. 1):
(a) The bottom layer is the
    stamped, grooved plastic.
(b) Above that lies a very thin
    film of aluminum (or chrome-
    aluminum alloy).   This
    metallic film reflects any
    light entering the disk from
    below, except where the pits
    fall in the plastic layer.
                                       ---
(c) Above the reflective metal
    layer is a coat of acrylic
    lacquer that protects the
    metal from scratches and
    oxidation.  It also allows
    printing descriptive labels
    safely on the top side of
    the disk.
                                       ---
The groove on the bottom surface
of a CD is a single channel that
spirals outward from the center
to the edge.  This track is
thinner than a human hair and
several kilometers long.
(The spiral differs from the
many concentric rings of iron
oxide (see Fig. 2) that store
information on a magnetic disk.)
                                       ---
The spindle through a CD's center
hole (see Fig. 3, d) connects
the disk to a variable-speed
motor (unlike the constant-speed
motor on a phonograph turntable).
                                       ---
The disk turns (clockwise) about
500 revolutions/minute (e) when
the reading laser beam is at the
center, but only about 200
revolutions/minute when the beam
reaches the outer edge.
This causes the track to pass
over the read-out system (f),
which gradually moves from the
center to the edge, at a
constant linear speed, to help
reliably detect the pits.
                                       ---
The moving spiral track is lined
with pits (dents) and flat spots
("lands").  These vary in size
and placement in a sequence that
represents the information stored.
The pit sequence can digitally
encode text, images, computer
programs, or the left- and right-
hand audio signals of a stereo
sound recording.
                                       ---
Additional pits
  * give location and timing
    information (for player
    display), and
  * control the motor speed
    so that the reading rate
    remains constant.
                                       ---
Two lenses and a semi-transparent
(partially silvered) mirror
(see Fig. 4) direct the laser
beam from below at the track on
the spinning CD.
                                       ---
If the laser beam strikes a pit
on the track (g), it is not
reflected.  The light-sensitive
photodiode (detector) below the
mirror sees no beam and produces
no signal.
If the laser beam strikes a land
between pits on the track (h),
it reflects back straight through
the mirror to the photodiode
below.  This detector then
produces an electric signal.
                                       ---
For compatibility with other
electronic equipment, a special
reversing circuit (a "not gate")
then turns these pit
interruptions into ON signals
(binary 1s) and turns the land
reflections into OFF signals
(binary 0s).
                                       ---

Annotated version:

Description Case 3:  Compact Disk

     Description                                  Analysis

Overview

A compact disk (CD), like a              FEATURE: comparison
phonograph record, stores                WHY: same role, parts
information physically for
electronic replay, and, like a
phonograph record, it stores the
information along a single spiral
groove on the side of a plastic
circle.

In contrast to a phonograph              FEATURE: contrast
record, however, a CD                    WHY: different behavior
  * stores the information in
    digital (on/off) rather than
    analog (variable shape) form,
    and
  * is read by reflected (laser)
    light, rather than by vibrating
    a needle that travels along the
    groove.

General Shape

     Size
A compact disk is a circle of            FEATURE: specifics
clear plastic (polycarbonate)            WHY: relevant to making
about 12 cm in diameter and
1 mm thick, with a 1.5-cm
diameter hole in the center.
CDs are stamped from a mold that
leaves a spiral track lined with
pits (little dents) on the CD's
bottom side (details below),
while the top side is smooth.

     Capacity
The surface area of a CD is just         FEATURE: contrast
less than twice (1.77 times) as          WHY: significance of parts
large as the surface area of a
3.5-inch magnetic "floppy" disk.
But because the pits store
information much more densely
than the iron oxide particles on
a floppy disk, a CD holds at
least 350 times more data (at
least 500 Mbyte on a CD, only
1.44 Mbyte a magnetic disk).

The Layers                               FEATURE: order of (dis)assembly
                                         WHY: large to small
CDs consist of three layers (see
Fig. 1):
(a) The bottom layer is the              FEATURE: parts
    stamped, grooved plastic.            WHY: show relation among them
(b) Above that lies a very thin
    film of aluminum (or chrome-
    aluminum alloy).   This
    metallic film reflects any           FEATURE: specifics
    light entering the disk from         WHY: show role
    below, except where the pits
    fall in the plastic layer.

(c) Above the reflective metal
    layer is a coat of acrylic
    lacquer that protects the
    metal from scratches and
    oxidation.  It also allows
    printing descriptive labels
    safely on the top side of
    the disk.

The Groove

     One-track Design
The groove on the bottom surface
of a CD is a single channel that
spirals outward from the center
to the edge.  This track is              FEATURE: comparison
thinner than a human hair and            WHY: explains data density
several kilometers long.
(The spiral differs from the             FEATURE: contrast
many concentric rings of iron            WHY: show role
oxide (see Fig. 2) that store
information on a magnetic disk.)

     Moving the Groove
The spindle through a CD's center
hole (see Fig. 3, d) connects
the disk to a variable-speed             FEATURE: contrast
motor (unlike the constant-speed         WHY: show role
motor on a phonograph turntable).

The disk turns (clockwise) about
500 revolutions/minute (e) when          FEATURE: specifics
the reading laser beam is at the         WHY: relevant to making
center, but only about 200
revolutions/minute when the beam
reaches the outer edge.
This causes the track to pass
over the read-out system (f),
which gradually moves from the
center to the edge, at a
constant linear speed, to help
reliably detect the pits.

The Pits

The moving spiral track is lined         FEATURE: specifics
with pits (dents) and flat spots         WHY: terminology
("lands").  These vary in size
and placement in a sequence that
represents the information stored.
The pit sequence can digitally           FEATURE: comparison (implicit)
encode text, images, computer            WHY: among pit roles
programs, or the left- and right-
hand audio signals of a stereo
sound recording.

Additional pits
  * give location and timing
    information (for player
    display), and
  * control the motor speed
    so that the reading rate
    remains constant.

The Optical Read-Out System

Two lenses and a semi-transparent        FEATURE: parts
(partially silvered) mirror              WHY: show relations
(see Fig. 4) direct the laser
beam from below at the track on
the spinning CD.

If the laser beam strikes a pit          FEATURE: specifics
on the track (g), it is not              WHY: relevant to making
reflected.  The light-sensitive
photodiode (detector) below the
mirror sees no beam and produces
no signal.
If the laser beam strikes a land
between pits on the track (h),
it reflects back straight through
the mirror to the photodiode
below.  This detector then
produces an electric signal.

For compatibility with other
electronic equipment, a special
reversing circuit (a "not gate")
then turns these pit
interruptions into ON signals
(binary 1s) and turns the land
reflections into OFF signals
(binary 0s).

Extended Activities:

Besides the primary activities explained above, you can have students pursue several secondary activities with the descriptive text of Exercise 3. These optional activities reinforce and (slightly) extend this exercise's original goals.

(1) SPELLING.
I always spell "compact disk" with a final "k," the standard in computing dictionaries and the spelling used by David Macaulay in The New Way Things Work as well. Students may notice (or you can point out) that on digital audio compact disks, the spelling printed on the lacquer layer is "disc" with a final "c." You can use this discrepancy to explain that every major publisher of technical descriptions (research departments, government agencies, publishing houses) has a style guide (a book of spelling, punctuation, and format rules) and settles such issues by appealing to the rules in their local guide. Different style guides yield different answers, as shown with "disc" and "disk."

(2) COMPARISONS.
As the middle of the description-writing guidelines points out, comparisons and contrasts often improve the usefulness of technical descriptions. They relate new features to familiar ones from other situations, and they clarify the significance of features whose value or contribution might otherwise remain obscure. (See also the "contrast class" discussion in the teacher notes on Exercise 0, Strategy, Part (4).)

Many comparisons and contrasts appear in the compact-disk description. You can ask students to find each one and discuss its role in the description, either on the (enlarged) text chunks used to reconstruct the description or on a separate copy of the whole text distributed just for that purpose. To help start this process, I include here a list of the most important comparisons and contrasts in Exercise 3:

     Comparison                             Paragraph

...like a phonograph record...                1 (twice)
In contrast to a phonograph record            2
...rather than analog...                      2
...rather than by vibrating a needle          2
...less than twice...as large                 4
...much more densely than                     4
...thinner than a human hair                  7
The spiral differs from...                    7
...unlike the constant-speed motor            8

(3) REWRITING, REVISING.
For every paragraph in a technical description, alternative versions exist that could have been used. Some are clearly better or worse that the original, while others involve tradeoffs that improve the description in one way but weaken it in another. (For background on the real-life relevance of text revision to laboratory science, see the teacher notes on Exercise 9.)

You can introduce students to this important idea that good writing demands revising, and revising requires carefully comparing the relative merits of alternative chunks of text. I have used paragraph 3 (on disk size) as the focus for such extended activity. You can present and discuss alternative versions of this paragraph (below) most easily in large-print format or by projecting them to large size on the wall.

• Version 1.
  The original version of the size paragraph (reproduced here) contains helpful signals for readers. But with only two sentences, each is very long (and hence harder to read). Have students count the words in each sentence and compute the total (shown below).

  A compact disk is a circle of
  clear plastic (polycarbonate)
  about 12 cm in diameter and
  1 mm thick, with a 1.5-cm              27 words
  diameter hole in the center.
  CDs are stamped from a mold that                 total = 56 words
  leaves a spiral track lined with
  pits (little dents) on the CD's
  bottom side (details below),           29 words
  while the top side is smooth.
  

• Version 2.
  You can ask able students to rewrite Version 1 using many short(er) sentences instead of just two long ones. You can also present less able students with an alternative text (shown here) that illustrates such a short-sentence revision. Have students count the words in each sentence in this (or their own) revised version and again compute the total. For the text shown here, each sentence is much shorter and easier, but the total paragraph size is actually 10% longer than the original. This tradeoff is typical, and students can discuss the new version's strengths and weaknesses compared to Version 1.

  A compact disk is a circle of
  clear plastic (polycarbonate).         10 words
  It is about 12 cm in diameter
  and 1 mm thick.                        11
  It has a 1.5-cm
  diameter hole in the center.            9
  CDs are stamped from a mold.            6
  The mold leaves a spiral track on                total = 63 words
  the bottom side (details below).       12
  The spiral track is lined with
  pits (little dents).                    9
  The CD's top side is smooth.            6
  

• Version 3.
  One technique to improve the usefulness and clarity of complex descriptions is to make information more explicit with overt lists (as suggested in the third part of the description-writing guidelines). You can ask able students to rewrite Version 1 (or 2) using an overt list of compact-disk features to make the text both clearer and shorter. You can also present less able students with an alternative text (shown here) that illustrates such an overt-list revision. Have students count the words in this revised version and again compute the total. For the text shown here, list format reduces the total word count to 47, which is 20% shorter than the original version. Lists must be used thoughtfully, of course, but this result typifies how they can improve technical descriptions.

  A compact disk is a circle of
  clear plastic (polycarbonate)
  with a
   * 12-cm diameter,
   * 1-mm thickness,
   * 1.5-cm diameter hole in
     the center,                                   total = 47 words
   * spiral track on its bottom
     side (stamped from a mold), and
   * smooth top side.
  The spiral track is lined with
  pits (little dents, details below).
  

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
Grade 3--"Read aloud fluently."
Grade 8--"Understand and explain the use of a complex mechanical device..." (p. 50).
Grade 9/10--"Critique the logic of functional documents...in anticipation of reader misunderstandings" (p. 57).
Grade 11/12--"Analyze both the features and the rhetorical devices of...public documents" (p. 66).
Writing:
Grade 7--"Revise writing to improve organization and word choice after checking the logic of the ideas and the precision of the vocabulary" (p. 44).
Grade 8--"Establish coherence within and among paragraphs" (p. 51).
Grade 9/10--"Write technical documents...report information and convey ideal logically and correctly...anticipate reader problems" (p. :61).

Exercise 4: Post-it Notes

(C) Text Reconstruction (Process).
Below I provide a "segmented" version of the student description of the Post-it note. It has the same text (without the scaffolding) as before, but marks (---) divide it into 16 sentence- (or predicate-)sized chunks. The descriptive chunks omit the headings, which appear in a separate short list for you to use as the project outline. Although much shorter than in Exercise 3, the text chunks still contain important signals or rhetorical clues about each chunk's intended role in and contribution to the overall description.

• Print out
  the segmented version of the Post-it description and cut it into pieces (of paper) along the marks (---) indicated.
• Enlarge
  each text chunk on a photocopy machine for easier in-class reading and sharing. Alternatively, use less enlargement and reassemble the description on a big table.
• Scramble
  the text pieces so that their original order is hidden.
• Distribute
  the (enlarged) text chunks randomly, one to each student (or perhaps to each pair of students).
• Read each piece aloud
  and try to find its best place. Use its internal rhetorical features (as mentioned on the guidelines) as clues and the list of headings as an organizing "target" framework, a broad outline of the intended result. Student discussion may perform most of this work in some classes; you will need to provide considerable leadership and encouragement in others since this is valuable but unfamiliar territory for many students. In some cases, even reading their text chunk aloud for classmates to consider may challenge the student who holds it.
• Post
  each text chunk on a wall or blackboard (with little pieces of tape or Post-it notes) as students decide on its preliminary role and place. But don't tape the paper sheets to each other unless you can easily undo them, because changing the order and grouping is a natural and appropriate part of reconstructing the whole description from its parts.
• Adapt
  the growing description as new pieces of the puzzle are read and reviewed. As in real life, first guesses may need to be revised to accommodate later arriving chunks of text that clarify the overall structure of the description that you are (re)building.
• Review
  the emerging whole as the last pieces fall into place, as you would with any puzzle. This approach enables students, cooperatively, to "write" a long, complex technical description using important, real-world design principles (the guidelines), without having to compose each separate piece of prose. It shows "actively" how the pieces of a good description have features that knit together to form a coherent pattern intended to help readers use the text well. Since the students must focus on those same text features to rebuild the description, they come to see why writers bother to deploy them.

Case:

Student version [headings only, for outline]:

Description Case 4:  Post-it Note


Overview

The Paper

The Adhesive

Student version [with scaffolding]:

Description Case 4:  Post-it Note

     Description                                  Analysis

Overview

A Post-it note is  an easy way           FEATURE:
to temporarily annotate a                WHY:
document by applying a small
square of colorful, durable
paper using a strip of
repositionable adhesive on the
back of the note.

The Paper                                FEATURE:
                                         WHY:
The most common Post-it notes
are 1.5-by-2-inch rectangles
of nonwhite (usually yellow)
paper available in pads of 100.

However, 55 larger sizes and
shapes (up to poster size) are
also available.

Post-it paper is well suited to          FEATURE:
making reliable notes because it:        WHY:

(1) does not tear or fray easily,
    even after repeated uses,

(2) is highly opaque, resisting          FEATURE:
    bleed-through from ink or            WHY:
    felt-tip pens, and

(3) comes in 29 colors that
    visually contrast with the
    document pages to which the
    notes are applied.

The Adhesive

The adhesive that holds the note
to its target page lies in a
half-inch strip along the top
edge of the back of each Post-it.

Post-it adhesive consists of             FEATURE:
tiny sticky spheres that do not          WHY:
easily dissolve or melt, and
that have about the same diameter
as the paper fibers they touch.

This adhesive therefore combines
several unusual properties.

First, the adhesive is clear and         FEATURE:
thinner than standard plastic            WHY:
mounting tape.

Second, unlike an adhesive               FEATURE:
bandage, it leaves no residue on         WHY:
the page to which the Post-it is
applied.

Third, the adhesive is long-
lasting while undisturbed;
Post-it notes will cling for
months (at room temperature)
before falling off their applied
surfaces.

And fourth, the adhesive is also
reusable.

A clean Post-it may be removed
and reapplied in the same or a
different location dozens of
times before the adhesive strip
fails to hold the note to its            FEATURE:
target (unlike most tape).               WHY:

Art Fry of 3M Corp. first                FEATURE:
developed the Post-it note in            WHY:
1980.

Student version [segmented, no scaffolding or headings]:

Description Case 4:  Post-it Note

                                       ---
A Post-it note is  an easy way
to temporarily annotate a
document by applying a small
square of colorful, durable
paper using a strip of
repositionable adhesive on the
back of the note.
                                       ---
The most common Post-it notes
are 1.5-by-2-inch rectangles
of nonwhite (usually yellow)
paper available in pads of 100.
                                       ---
However, 55 larger sizes and
shapes (up to poster size) are
also available.
                                       ---
Post-it paper is well suited to
making reliable notes because it:
                                       ---
(1) does not tear or fray easily,
    even after repeated uses,
                                       ---
(2) is highly opaque, resisting
    bleed-through from ink or
    felt-tip pens, and
                                       ---
(3) comes in 29 colors that
    visually contrast with the
    document pages to which the
    notes are applied.
                                       ---
The adhesive that holds the note
to its target page lies in a
half-inch strip along the top
edge of the back of each Post-it.
                                       ---
Post-it adhesive consists of
tiny sticky spheres that do not
easily dissolve or melt, and
that have about the same diameter
as the paper fibers they touch.
                                       ---
This adhesive therefore combines
several unusual properties.
                                       ---
First, the adhesive is clear and
thinner than standard plastic
mounting tape.
                                       ---
Second, unlike an adhesive
bandage, it leaves no residue on
the page to which the Post-it is
applied.
                                       ---
Third, the adhesive is long-
lasting while undisturbed;
Post-it notes will cling for
months (at room temperature)
before falling off their applied
surfaces.
                                       ---
And fourth, the adhesive is also
reusable.
                                       ---
A clean Post-it may be removed
and reapplied in the same or a
different location dozens of
times before the adhesive strip
fails to hold the note to its
target (unlike most tape).
                                       ---
Art Fry of 3M Corp. first
developed the Post-it note in
1980.
                                       ---

Annotated version:

Description Case 4:  Post-it Note

     Description                                  Analysis

Overview

A Post-it note is  an easy way           FEATURE: overview
to temporarily annotate a                WHY: show role
document by applying a small
square of colorful, durable
paper using a strip of
repositionable adhesive on the
back of the note.

The Paper                                FEATURE: parts
                                         WHY: show role(s), relations
The most common Post-it notes
are 1.5-by-2-inch rectangles
of nonwhite (usually yellow)
paper available in pads of 100.

However, 55 larger sizes and
shapes (up to poster size) are
also available.

Post-it paper is well suited to          FEATURE: specifics
making reliable notes because it:        WHY: relevant to use

(1) does not tear or fray easily,
    even after repeated uses,

(2) is highly opaque, resisting          FEATURE: comparison (implicit)
    bleed-through from ink or            WHY: show role(s)
    felt-tip pens, and

(3) comes in 29 colors that
    visually contrast with the
    document pages to which the
    notes are applied.

The Adhesive

The adhesive that holds the note
to its target page lies in a
half-inch strip along the top
edge of the back of each Post-it.

Post-it adhesive consists of             FEATURE: specifics
tiny sticky spheres that do not          WHY: relevant to making
easily dissolve or melt, and
that have about the same diameter
as the paper fibers they touch.

This adhesive therefore combines
several unusual properties.

First, the adhesive is clear and         FEATURE: comparison (overt)
thinner than standard plastic            WHY: relevant to use
mounting tape.

Second, unlike an adhesive               FEATURE: contrast
bandage, it leaves no residue on         WHY: relevant to use
the page to which the Post-it is
applied.

Third, the adhesive is long-
lasting while undisturbed;
Post-it notes will cling for
months (at room temperature)
before falling off their applied
surfaces.

And fourth, the adhesive is also
reusable.

A clean Post-it may be removed
and reapplied in the same or a
different location dozens of
times before the adhesive strip
fails to hold the note to its            FEATURE: contrast
target (unlike most tape).               WHY: relevant to use

Art Fry of 3M Corp. first                FEATURE: omit this!
developed the Post-it note in            WHY: irrelevant
1980.

Extended Activities:

Besides the primary activities explained above, you can have students pursue secondary activities with the descriptive text of Exercise 4. See Exercise 3 for general suggestions also applicable here.

POSSIBLE FIGURES.
Because Exercise 4 has no supporting illustration, you can have students explore text-graphics integration by asking them to:
(A) develop (sketch) one or more possible figures for this description, or
(B) compare the relative merits of several possible figures that you offer for this description.

Because Post-it notes are so visually simple, mere photographs or drawings of the product (as for advertising) add little or no value to the descriptive text. (See the comments about drawn technical art near the start of the Strategy notes for Exercise 2.) Explanatory diagrams are what we need. Consider a drawing that shows the adhesive strip limited to the top back portion of each Post-it sheet (this explains why you can easily remove Post-its: they only stick along one edge, by design). Or consider a drawing that shows the spheres of adhesive clinging to gaps in criss-crossed paper fibers about as big as the adhesive particles (this shows how the repositionable adhesive works). If you or a colleague (or a student) can sketch and share such possible supporting figures, you can focus student attention on why technical art, like technical text, needs careful design to really help readers.

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
Grade 3--"Read aloud fluently."
Grade 5--"Understand how text features make information accessible and usable" (p. 28).
Grade 9/10--"Critique the logic of functional documents...in anticipation of reader misunderstandings" (p. 57).
Grade 11/12--"Analyze both the features and the rhetorical devices of...public documents" (p. 66).
Writing:
Grade 8--"Establish coherence within and among paragraphs" (p. 51).
Grade 9/10--"Write technical documents...report information and convey ideal logically and correctly...anticipate reader problems" (p. 61).
Grade 11/12--"Enhance meaning by employing...visual aids" (p. 69).

Exercise 5: Fluorescent Lamp

HOW TO USE THIS EXERCISE:

(A) Role Recognition (Deprecated).
Although you can certainly use the text of Exercise 5 for more practice in recognizing the features of a description and their roles, no student version with scaffolded feature prompts is provided (and, hence, no annotated teacher version either). My experience is that by the time they reach Exercise 5, all students need the greater activity level that text reconstruction (below) offers.

(B) Text Reconstruction (Background).
Reconstructing Exercise 5 from its scrambled sentence-length pieces involves the same practical, work-relevant attention to text features and linguistic clues as did Exercise 3 (which introduces this activity) and Exercise 4. Note that the pieces here are (a) more fine grained, calling for more student attention to their details, and (b) more numerous (making twice as large a reconstruction project as the previous exercises).

(C) Text Reconstruction (Process).
Below I provide a "segmented" version of the student fluorescent-lamp description. It has no scaffolding, but marks (---) divide it into 30 sentence-sized chunks. The descriptive chunks omit all high-level headings, which appear in a separate list for you to use as the project outline. Although the text chunks are short, each contains signals or rhetorical clues (including lowest-level or "run-in" headings and figure callouts) about each chunk's intended role in and contribution to the overall description.

• Print out
  the segmented version of the fluorescent-lamp description and cut it into pieces (of paper) along the marks (---) indicated.
• Enlarge
  each text chunk on a photocopy machine for easier in-class reading and sharing. Everyone can participate more easily if the description parts (that you assemble as puzzle pieces on the wall) have print big enough to read from across the room. Alternatively, use less enlargement and reassemble the description on a big table.
• Scramble
  the text pieces so that their original order is hidden.
• Distribute
  the (enlarged) text chunks randomly, one to each student (or perhaps to each pair of students). GROUPS VERSION: Teachers who prefer that students work in small groups can easily adapt Exercise 5 for small-group practice. Make enough complete sets of the description text chunks so that each group of students can have one whole set. Scramble the text pieces within each set and let the students of each group cooperatively reassemble the description from their set of pieces as best they can. Then have one group post their reconstructed description on the wall for you (or them) to read, adapt, and evaluate (as below).
• Read each piece aloud
  and try to find its best place. Use its internal rhetorical features (as mentioned on the guidelines) as clues and the list of headings and the figures as an organizing "target" framework, a broad outline of the intended result. Student discussion may perform most of this work in some classes; you will need to provide considerable leadership and encouragement in others since this is valuable but unfamiliar territory for many students. In some cases, even reading their text chunk aloud for classmates to consider may challenge the student who holds it.
• Post
  each text chunk on a wall or blackboard (with little pieces of tape or Post-it notes) as students decide on its preliminary role and place. But don't tape the paper sheets to each other unless you can easily undo them, because changing the order and grouping is a natural and appropriate part of reconstructing the whole description from its parts.
• Adapt
  the growing description as new pieces of the puzzle are read and reviewed. As in real life, first guesses may need to be revised to accommodate later arriving chunks of text that clarify the overall structure of the description that you are (re)building.
• Review
  the emerging whole as the last pieces fall into place, as you would with any puzzle. This approach enables students, cooperatively, to "write" a long, complex technical description using important, real-world design principles (the guidelines), without having to compose each separate piece of prose. It shows "actively" how the pieces of a good description have features that knit together to form a coherent pattern intended to help readers use the text well. Since the students must focus on those same text features to rebuild the description, they come to see why writers bother to deploy them.

Case:

Student version [headings only, for outline]:

Description Case 5:  Fluorescent Lamp



Overview


Structure

     Size


     Contents


     Labels


Operation

     Gas Discharge

          STARTING.

          EMITTING.

          VISIBILITY.


     Wavelength Conversion


     Efficiency

          HEAT/LIGHT RATIO.

          BULB LONGEVITY.

Student version [segmented, no scaffolding or headings]:

Description Case 5:  Fluorescent Lamp

                                       ---

A fluorescent lamp is a long
straight glass tube that glows
when a current passing through
low-pressure gas within the tube
causes a coating on the glass to
emit white light.
                                       ---
Fluorescent lamps were first
introduced commercially in 1938.
                                       ---
A standard fluorescent lamp is a
cylindrical glass tube 1.5 inches
in diameter and 48 inches long
(other sizes are available).
                                       ---
A 2-pin metal base or cap seals
each end of the tube (see Fig. 1).
                                       ---
Inside each end cap, attached to
the pins, is a filament or
electrode, a thin thread of wire
from which electrons boil when it
is heated by an electric current.
                                       ---
Sealed within the tube by the
caps is a drop of mercury and a
very low-pressure inert gas
(usually argon).
                                       ---
A light-emitting chemical (see
the Operation section) called a
phosphor coats the entire inside
surface of the glass.
                                       ---
Fluorescent lamps carry
standardized labels outside that
identify their internal physical
and electrical properties.
                                       ---
For example, a lamp with the
black characters
     F40-T12
stenciled on one end is a
fluorescent (F) tube (T) that
uses 40 watts of power and has
a diameter of 12 eighths of an
inch (12/8 = 3/2 = 1.5 inch).
                                       ---
STARTING.  When the lamp is off,
the mixture of mercury and gas
inside does not conduct
electricity.
                                       ---
So every fluorescent lamp is
attached to a starting device
called a ballast, which combines
 * a "transformer" to produce an
   initial, high-voltage burst,
   and
 * an "inductor" to limit
   current flow while the lamp
   is on.
                                       ---
EMITTING.  When power is first
applied, a 250- to 400-volt burst
of electricity vaporizes the
mercury (see Fig. 1, left).
                                       ---
Electrons in the mercury atoms
absorb energy and jump to
"higher," more energetic orbits
(Fig. 1, middle).
                                       ---
They then fall back to less
energetic orbits (Fig.1, right).
                                       ---
This repeating process, called
gas discharge,  continuously
emits the absorbed energy as
light.
                                       ---
Once started, only about 175 volts
are needed to maintain this
discharge in a 40-watt lamp.
                                       ---
VISIBILITY.  When an applied
voltage causes discharge in some
low-pressure, inert gases, they
emit visible light.
                                       ---
Ionized neon gas emits red
light, for example, seen
directly in a glowing neon bulb.
                                       ---
But in a fluorescent lamp, the
discharge comes almost entirely
from the mercury vapor, even
though it is only 1 percent of
the enclosed gas.
                                       ---
And almost all of the mercury
discharge is ultraviolet (UV)
light, whose wavelength is too
short for human eyes to see.
                                       ---
The phosphor that coats the
inside of the lamp tube converts
the UV mercury discharge into
useful light that people can see.
                                       ---
The phosphor absorbs the
invisible, short-wave UV
emissions from the excited
mercury atoms (Fig. 1, right).
                                       ---
It then emits other light with
a longer wavelength, almost all
of which is visible.
                                       ---
The chemical composition of the
phosphor lining the tube controls
the color of the visible light
emitted, which may be
 * "cool white" (partly blue), or
 * "warm white" (partly pink), or
 * other visible colors.
                                       ---
HEAT/LIGHT RATIO.  All lamps
convert current into visible
light and heat.
                                       ---
Fluorescent lamps are about 2 to
4 times more efficient than
incandescent (glowing filament)
lamps.
                                       ---
For the same power, they produce
2 to 4 times more light and less
heat.
                                       ---
BULB LONGEVITY.  Fluorescent
lamps also have longer lifetimes.

A typical incandescent bulb lasts
1000 hours before the filament
fails.
                                       ---
But a typical fluorescent lamp
lasts 10,000 to 20,000 hours,
depending on how often it is
started.

                                       ---

Annotated version:

Description Case 5:  Fluorescent Lamp


Overview

A fluorescent lamp is a long
straight glass tube that glows
when a current passing through
low-pressure gas within the tube
causes a coating on the glass to
emit white light.

Fluorescent lamps were first
introduced commercially in 1938.

Structure

     Size

A standard fluorescent lamp is a
cylindrical glass tube 1.5 inches
in diameter and 48 inches long
(other sizes are available).

A 2-pin metal base or cap seals
each end of the tube (see Fig. 1).

     Contents

Inside each end cap, attached to
the pins, is a filament or
electrode, a thin thread of wire
from which electrons boil when it
is heated by an electric current.

Sealed within the tube by the
caps is a drop of mercury and a
very low-pressure inert gas
(usually argon).

A light-emitting chemical (see
the Operation section) called a
phosphor coats the entire inside
surface of the glass.

     Labels

Fluorescent lamps carry
standardized labels outside that
identify their internal physical
and electrical properties.

For example, a lamp with the
black characters
     F40-T12
stenciled on one end is a
fluorescent (F) tube (T) that
uses 40 watts of power and has
a diameter of 12 eighths of an
inch (12/8 = 3/2 = 1.5 inch).

Operation

     Gas Discharge

STARTING.  When the lamp is off,
the mixture of mercury and gas
inside does not conduct
electricity.

So every fluorescent lamp is
attached to a starting device
called a ballast, which combines
 * a "transformer" to produce an
   initial, high-voltage burst,
   and
 * an "inductor" to limit
   current flow while the lamp
   is on.

EMITTING.  When power is first
applied, a 250- to 400-volt burst
of electricity vaporizes the
mercury (see Fig. 1, left).

Electrons in the mercury atoms
absorb energy and jump to
"higher," more energetic orbits
(Fig. 1, middle).

They then fall back to less
energetic orbits (Fig.1, right).

This repeating process, called
gas discharge,  continuously
emits the absorbed energy as
light.

Once started, only about 175 volts
are needed to maintain this
discharge in a 40-watt lamp.

VISIBILITY.  When an applied
voltage causes discharge in some
low-pressure, inert gases, they
emit visible light.

Ionized neon gas emits red
light, for example, seen
directly in a glowing neon bulb.

But in a fluorescent lamp, the
discharge comes almost entirely
from the mercury vapor, even
though it is only 1 percent of
the enclosed gas.

And almost all of the mercury
discharge is ultraviolet (UV)
light, whose wavelength is too
short for human eyes to see.

     Wavelength Conversion

The phosphor that coats the
inside of the lamp tube converts
the UV mercury discharge into
useful light that people can see.

The phosphor absorbs the
invisible, short-wave UV
emissions from the excited
mercury atoms (Fig. 1, right).

It then emits other light with
a longer wavelength, almost all
of which is visible.

The chemical composition of the
phosphor lining the tube controls
the color of the visible light
emitted, which may be
 * "cool white" (partly blue), or
 * "warm white" (partly pink), or
 * other visible colors.

     Efficiency

HEAT/LIGHT RATIO.  All lamps
convert current into visible
light and heat.

Fluorescent lamps are about 2 to
4 times more efficient than
incandescent (glowing filament)
lamps.

For the same power, they produce
2 to 4 times more light and less
heat.

BULB LONGEVITY.  Fluorescent
lamps also have longer lifetimes.

A typical incandescent bulb lasts
1000 hours before the filament
fails.

But a typical fluorescent lamp
lasts 10,000 to 20,000 hours,
depending on how often it is
started.

Extended Activities:

Besides the primary activities explained above, you can have students pursue several secondary activities with the descriptive text of Exercise 5. These optional activities reinforce and (slightly) extend this exercise's original goals. See Exercise 3 for general suggestions also applicable here.

REWRITING, REVISING.
For every paragraph in a technical description, alternative versions exist that could have been used. Some are clearly better or worse that the original, while others involve tradeoffs that improve the description in one way but weaken it in another. (For background on the real-life relevance of text revision to laboratory science, see the teacher notes for Exercise 9.)

You can introduce students to this important idea that good writing demands revising, and revising requires carefully comparing the relative merits of alternative chunks of text. I have used paragraph 5 (on the electrode, first within the "Contents" subsection) as the focus for such extended activity. You can present and discuss alternative versions of this paragraph (below) most easily in large-print format or by projecting them to large size on the wall.

• Version 1.
  The original version of the electrode paragraph (reproduced here) is very concise. But it involves a single long, complex (though clear) sentence, potentially difficult for nonnative English readers to understand. Have students count the total words used in this version.

  Inside each end cap, attached to
  the pins, is a filament or
  electrode, a thin thread of wire                 total = 30 words
  from which electrons boil when it
  is heated by an electric current.
  

• Version 2.
  You can ask able students to rewrite Version 1 as many short sentences that make explicit each assertion embedded within it (or show them Version 2 below). Version 2 spells out every implicit claim made in Version 1: the result is four very easy sentences, but sentences that give each claim an equal linguistic emphasis, for a repetitious, annoyingly flat tone. Have students count the total words here too. At 38 words, this is not only much more awkward than Version 1 but it is 25% longer as well.

  A filament attaches to the
  pins inside each end cap.
  A filament is an electrode.
  A filament is a thin thread
  of wire.                                         total = 38 words
  Electrons boil from a filament
  when a filament is heated by
  an electric current.
  

• Version 3A, B.
  You can ask students to rewrite Version 2 with the goal of keeping the simplicity but improving the focus and emphasis (or show them Version 3A, below). Version 3A makes the same claims as Version 2 but introduces some linguistic signals and verbal combinations to save text and make a more readable result:

  A filament or electrode          (3A)
  attaches to the pins inside
  each end cap.
  This is a thin thread of wire.
  From it electrons boil when
  heated by an electric current.
  

  Version 3A, however, introduces two different (unintended, but typical) mistakes or verbal flaws that will mislead readers.
  (1) The second sentence begins with the wrong pronoun. "It is a thin thread..." would refer back to the beginning of the first sentence (whose subject is "a filament"). "This is a thin thread..." refers to the end of the first sentence, to the noun immediately before the pronoun (here, to "end cap"). Using a pronoun to bridge the two sentences is a good strategy, but this is an inappropriate, misleading choice. Version 3B (below) shows where "this" takes the topic of the description (which is not the original intention here).

  A filament or electrode          (3B)
  attaches to the pins inside
  each end cap.
  This [cap] is made of aluminum.
  

  (2) The third sentence in Version 3A contains the ambiguous phrase "when heated." Is the electrode heated or rather the electrons that boil off? Adding another pronoun here can eliminate the danger of misreading this sentence (as in Version 4, below).
• Version 4.
  This version keeps the strengths of Version 3A but removes its weaknesses, and it eliminates the unwanted detour of meaning in Version 3B:

  A filament or electrode
  attaches to the pins inside
  each end cap.
  It is a thin thread of wire.
  From it electrons boil when
  it is
  heated by an electric current.
  

  Version 4 preserves all the claims made in Version 1, offers (three) simplier sentences to the reader, and yet maintains the proper thread of continuity too. Version 4 is virtually the same length as Version 1 (31 words); this suggests that improving on the conciseness of Version 1 is quite hard, but one can (perhaps) improve it somewhat in other, more subtle ways. Able students can compare the benefits of Version 1 and Version 4 as serious text alternatives.

Note:

This exercise most closely supports the following 1998 California English-Language Arts content standard(s).
Reading:
Grade 3--"Read aloud fluently..."
Grade 8--"Understand and explain the use of a complex mechanical device" (p. 50).
Grade 9/10--"Critique the logic of functional documents by examining the sequence of information and procedures in anticipation of possible reader misunderstandings" (p. 57)