The odd one out

What the other figures all share

提示Find the family before you go looking for the stranger.

为什么Four of the five belong together in one way. Naming that link out loud turns a vague hunt into a single question you can answer: which one fails it?

One feature at a time

提示Check the outlines first, then the shading, then the small details.

为什么Run down the whole group asking one thing — do they all have the same number of sides? — then ask the next. Comparing everything at once is how a difference slips past you.

From the figures printed on the left

提示Solve the small set first; only then read what you may choose.

为什么Deciding the rule before you look at the options stops a tempting picture from bending your reasoning. Read the group, name the link, then choose.

No — three gives you more evidence

提示An extra view of the same thing can only help you.

为什么Each figure in the group is another view of one shape, so the link is easier to confirm, not harder. Use the third one to check the rule you read from the first two.

No — check the others do not differ that way too

提示Every picture is unlike the rest in some tiny detail.

为什么In a sound question exactly one figure breaks the shared rule. If two of them break it, you have found the wrong rule — go back and look for another.

That every remaining figure obeys the rule

提示Prove the family, not just the stranger.

为什么Say the rule to yourself and try it on each of the others in turn. A rule that holds for all but one gives you the answer; a rule that holds for only two is not a rule at all.

Yes — position can be the sorting rule

提示Notice whether it hugs a corner or floats in the middle.

为什么Children often look only at the shapes and miss where they sit. High or low, left or right, touching an edge or clear of it — any of that can be what splits the group.

How many lines each one has

提示A number is far easier to compare than a picture.

为什么Counting turns a fuzzy look-and-see into something you can hold on to. Count lines, count corners, count the small shapes inside — then compare the numbers instead of the whole figures.

Being symmetrical is the shared feature

提示Fold each picture down the middle in your head.

为什么A line of symmetry is a favourite sorting rule because it is easy to see once you go looking for it. Try the fold down the middle first, then the fold across.

4

提示All of them but the stranger.

为什么Five are printed and one is the odd one, so four share the rule. If you can only make three of them agree, the rule you have picked is the wrong one.

2

提示Just enough to show a link — a pair.

为什么Two or three figures are shown. Two is the least it can be, because a single picture could never tell you what the group has in common.

shared and breaks

提示One word for what they have in common; one for what the stranger does to it.

为什么Naming both halves out loud is the whole method: the rule, then the exception. Skipping the first half is exactly why a tempting-looking picture gets picked.