Two files can look almost identical while only one meets the task. Showing a correct example beside a carefully chosen near-miss can help a learner notice the decision that matters.
Start with a harmless practice task: make a document where the title can appear in the navigation outline. One version uses an actual heading style; another merely has enlarged bold text. Ask what evidence would distinguish them, rather than which looks prettier.
Let the learner inspect the relevant feature and explain the difference. If they cannot, demonstrate that single check. Avoid adding unrelated errors, because a page full of mistakes makes it unclear what the comparison is meant to teach.
Then change the visible styling so the functional version looks different from the original example. Can the learner still identify why it works? This step tests the rule rather than recognition of one screenshot.
Keep the near-miss safe
Use copies and fictional content. Do not demonstrate mistakes through real payments, sharing permissions or destructive file operations. Label both versions as practice material so an incorrect example is not accidentally reused as instructions.
End by asking the learner to make a third version and describe how they checked it. The result should be a usable decision rule, such as “inspect the applied style and the outline,” rather than a preference for the file that resembles the teacher’s example.
Image: an editorial illustration, not a documentary photograph.