Which One Doesn’t Belong?

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.



  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. 🙂

  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 ..

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