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Context for this case:
Prerequisites:
Cognitive Apprenticeship Features:
Supporting References:
Relevant CA Content Standards |
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(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.TEXT ANALYSIS:
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.
(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.
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.
(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).
Contact: T. R. Girill trgirill@acm.org