The odd one out

What the other figures all share

HintFind the family before you go looking for the stranger.

The whyFour 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

HintCheck the outlines first, then the shading, then the small details.

The whyRun 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

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

The whyDeciding 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

HintAn extra view of the same thing can only help you.

The whyEach 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

HintEvery picture is unlike the rest in some tiny detail.

The whyIn 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

HintProve the family, not just the stranger.

The whySay 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

HintNotice whether it hugs a corner or floats in the middle.

The whyChildren 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

HintA number is far easier to compare than a picture.

The whyCounting 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

HintFold each picture down the middle in your head.

The whyA 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

HintAll of them but the stranger.

The whyFive 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

HintJust enough to show a link — a pair.

The whyTwo 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

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

The whyNaming 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.