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Re: ALT text usage for Geology test questions

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From: Tyllick,Cliff S (HHSC/DADS)
Date: Oct 25, 2016 5:28PM

Hi, Jason!



What a fantastic example of the distinction between 'text equivalent- and 'meaning-!



Usually, even if we say 'text equivalent,- our brain short circuits to 'the meaning of an image.- For example, in 'I [image of heart] you,- the alt text for that image should be 'love.- Is that the 'text equivalent- or the 'meaning-? Well, it's both-so by relying on that example, we might understand one thing (alt text = meaning) when we say we understand another (alt text = text equivalent).



In your example, the text equivalent of the image is a question: 'What is this?- OK, that's way too general, but you seem to be on the right track with your misgivings about using a textbook definition of quartz as the alt text: 'a hard white or colorless mineral consisting of silicon dioxide, found widely in igneous, metamorphic, and sedimentary rocks.-



If that were the text equivalent of the image, you would have a multiple choice question-something like this:



Quartz is:

a) the plural of 'quart- in German.

b) a subatomic particle, distinguished in part by its charm.

c) a hard white or colorless mineral consisting of silicon dioxide, found widely in igneous, metamorphic, and sedimentary rocks. [The correct answer is always 'c,- right?]

d) All of the above.

e) a) and c), but not b).



So let's think of how we can present the information in the image as a question, not an answer. (Gee, we're playing alt-Jeopardy! - with apologies to people not familiar with the game show.)



Here are points I would consider:

· Does anything in the image tell me that the substance is hard? If not, don't use that word. Maybe it has sharp edges, and I can infer from those that it is hard, but I can't 'see- hardness. So if sharp edges is a clue I should be looking for, tell me that they're there-but don't tell me what they mean, because presumably you're testing for that.

· If anyone can tell it's silicon dioxide by looking at it, keep them away from kryptonite! I don't know geology, but I do know X-ray crystallography, and it would take X-ray vision and sophisticated software to tell what elements are in a crystalline substance. So obviously that isn't helpful in the alt text.

· The definition says quartz is 'found widely in igneous, metamorphic, and sedimentary rocks.- But is the rock in the image all three of those? Presumably it's mainly one or two. What features would I have to perceive in the image to determine which one-or ones-are present? In the alt text, describe those features-but don't give away the meaning.

· If the image is a chunk of quartz completely isolated from the source rock, how would I know what kind of rock it came from? I assume that I wouldn't. But if there is something telltale that suggests this is quartz from a particular type of rock, describe that feature in the alt text-but don't tell what it means.

· What's the point of the ruler? Yes, I know it establishes scale, but what is that scale? Is the ruler calibrated in millimeters? Centimeters? Sixteenths of an inch? Some other base unit? Then give me that information, as presented by the ruler. In other words, you could say '11.4 mm wide- if the ruler is calibrated to the millimeter, but you couldn't say '11.39 mm wide--so convey significant digits and estimations to the extent that would be standard in this field.

· Is irrelevant or inconclusive information present? If so, would you expect a sighted student to notice it and have to screen it out to get to the answer? For example, the definition says that quartz can be milky or clear. What if this rock is so milky it looks almost solid white? In the alt text, give that feature of this rock, not the definitive range of possibilities for quartz.



Follow that train of thought and I think you will come up with the right answer. And don't worry about keeping it short-in most cases you might need a long description (now aria-describedby), not alt text.



You could do both. What if you set the problem up so the student had to identify quartz from a collection of crystal-forming substances? I'm going out on a limb with my geologic knowledge, so indulge me if the specific examples don't make perfect sense. It's the approach that matters:

· Show the students images of quartz, iron pyrite, calcite, and diamond.

· Iron pyrite-fool's gold, as you know-should be easy to tell from the others, because it has a metallic appearance. That level of detail could be in the alt text of each image.

· The aria-describedby attribute should lead the student to a rich description of the image-as much detail as is available, including whatever they should use to tell the difference between calcite and quartz and diamond. (Maybe it could be a chocolate diamond-is that a natural substance?-so they would have to figure out whether the brownish color mattered.)

· Just to reinforce: Yes, include this rich level of detail for the pyrite, too. A blind student who follows that path after hearing the alt text will listen to a lot of irrelevant information, but wouldn't that be just like the sighted student who fixates on the details of the image when a glance should rule it out? It would be a result of their error in judgment, not an experience you are forcing on them.



So you asked for alt text and I've given you a long description. Bottom line, I encourage you to consider what it is you are trying to assess: Whether a student enters the correct answer? Or whether the student uses the available information as a geologist would to get to the best answer? (Maybe, even though only the first image is quartz, the best answer is, 'It's either the first or the third, because the available information doesn't let us tell those quartz and diamond apart.-) If you shoot for the more sophisticated assessment, you'll have an easier time writing alt text (and longer descriptions), and the right students might find your exams more interesting-perhaps even fun.



Best to you,


Cliff

Cliff Tyllick
EIR Accessibility Coordinator
Texas Health & Human Services Commission
512-438-2494
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