01
Choose the rule before arranging the examples
Write the criterion in ordinary language at the top of the sheet: place shapes with a curved part in one group and shapes made only of straight segments in another. Draw a circle, a triangle and a shape with both a straight and a curved edge. Keep the drawings simple enough that their outlines can be inspected. Label the groups with the criterion rather than relying on colour alone. The mixed-edge example is useful because it requires applying the stated rule, instead of guessing that the groups are simply circles and everything else.
02
Include a contrasting case and state why it belongs
Place each example under a label and add a short explanation. The triangle belongs with straight segments; the mixed-edge shape belongs with curved parts because the rule asks whether any curved part is present. Add a new outline and ask the reader to explain where it belongs. Avoid changing the criterion halfway through the sheet. If a drawing makes the relevant edge unclear, redraw it or mark the ambiguity for discussion. A confusing illustration is a property of the exercise to resolve, not evidence about the reader’s reasoning.
03
Keep the answer and the explanation together
Prepare an answer version with the same drawings, group labels and a sentence explaining each placement. Ask a reviewer to identify what rule they understood and which example needed clarification, then record their actual comments. Revise the wording or drawing if those comments reveal a mismatch with the intended task. Keep the original sheet and the revised version so the change is traceable. The finished packet contains the rule, labelled groups, a contrasting example, a new case and an explanation. It can serve as a starting point for another visual exercise with a different explicitly stated criterion.