Which One Doesn't Belong?: A Shapes Book

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A speech bubble out of the yellow shape over 2:3 appears that reads: Ok, so this one doesn’t work. Why else might 5 not belong? Learn about the NSW education department, who we are and how we operate. Explore our people, accountabilities, jobs, opportunities and much more. In the bottom right corner: 4 triangles are joined at the points form a big purple and green square. What's the reason why this domino doesn't belong? Ah, yes, I had noticed the same thing that some of you noticed… Under the starburst, a blue text box appears with text: Can you make a case for why each one doesn’t belong?] Speaker

A speech bubble out of the yellow shape appears that reads: This one shows a doubles fact. It’s the only one to show a double.]

Shape 46

In the bottom left corner: 4 triangles are joined alternating on their angled sides to form a parallelogram.] Speaker They also agreed that Sarah’s reasoning was correct. One student then said, “You mean we are all correct?” The conversation had reached a turning point. As we explored more sets of figures, I didn’t hear, “I disagree” or “I think you’re wrong”. Instead, I heard “ Wow, I didn’t think of that” and “I saw something different”. Yeah, three is an odd number because if I halve it, I'd have one left over. 11 is an odd number because if I halved it, there would be one left over. And five is an odd number because if I halved it there'd be one left over. Mm-hmm.

I was inspired by the work of Christopher Danielson, so I started creating my own WODB activities geared towards students in elementary and middle school. My classes thoroughly enjoyed this book and our conversations about shapes. It generated deep thinking and brought up a few questions that we are still wondering about. In a good way!’ So what about this one? What's one reason why this one doesn't belong? OK. Yes, it's... Oh, I almost said it's the only domino with three on it, but it's not actually. Makes sense, doesn’t it? But, is it mathematically correct? I don’t know. My students gave me some pretty good arguments justifying their reasoning! We decided we needed to do some research on the word scalene. Does it only apply to triangles?

Number 27

I think it would also be very interesting to have the students write their own reflections. Did they find this activity interesting and why? What do they think they learned from this activity? These are examples non-statistical questions because they are answered by collecting data that does not vary: With your group, decide what the responses for question number 1 have in common. Then do the same for questions numbered 2 and 3. Which One Doesn't Belong? is a brilliant new math book from Stenhouse. A MUST-HAVE if you teach math at any age I think. How many students are on the roster for this class?” would produce numerical data that does not vary. There is only one value in the data set, so there is no variability.