TACHS: Ability: figure classification

A method you can use

1. Find a property shared by all three reference figures and test each alternative against that property. Start with shape type, containment, line relationships, fill, symmetry and count. Size or orientation can vary while a deeper structural relationship stays fixed.
2. Original example: three different outlined polygons each contain exactly one filled circle. An outlined triangle containing one filled circle can join the group. A similar triangle with two filled circles fails the count rule, while one containing an outline circle fails the fill rule.
3. A proposed rule must fit every reference figure. If two examples have vertical symmetry and the third does not, vertical symmetry cannot define the class. Compare the closest alternative feature by feature instead of choosing the figure that simply looks most like the first example.
4. Transfer: three reference figures each show two line segments crossing once in their interiors. A rotated pair with one interior crossing belongs. Two segments touching only at an endpoint do not, because touching and crossing are different relationships. Confirm that the selected alternative satisfies the property rather than a distracting resemblance.

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Related section practice

30 practice questions cover this skill. Try a set below or use the question bank for more.