## Which One Doesn’t Belong?

I like Odd-One-Out puzzles that are ambiguous. That is why I bought the book Which One Doesn’t Belong? Look at the cover: which is the odd one out? The book doesn’t include answers, but it has nine more examples in each of which there are several possible odd-one-outs.

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1. #### Jo in OKC:

The teachers book for this is great. It looks like you got the student book.
The biggest challenge is to find a reason each one of the 4 things doesn’t belong.
Some sample reasons for the cover shapes
* Top Left: Is a regular hexagon.
* Top right: Is concave. All others are convex. Also, can be divided into 3 squares. Every angle is a right angle.
* Bottom Left: Every side is a different length
* Bottom Right: Has 5 sides/is a pentagon. All others have 6.

2. #### Al Yunani:

Nice one, Tanya!
I would guess that the “odd” depends very much on one’s background and nature. I would bet that a painter or artist in general, would reply with no hesitation bottom left, since it is the only “ugly” one. Mathematical interpretation of “ugly” :the only one without an axis of symmetry. Symmetry is important! More important than concavity. ðŸ™‚

3. #### Shiri:

I bet they mean the hexagon, since each of the others doesn’t belong (non-convex, sides of not-equal length, and diff number of sides) so the hexagon is odd in that it does belong with any of the other two in an easily defined class. No?

4. #### Jaijith:

First is regular hexagon. Second is irregular hexagon ; Third one ( on left)is an irregular hexagon as well ,,,so the fourth which is a pentagon stands as odd ..