As with any task, whether it’s a warmup or a curricular task, I try to think of ways to get more student engagement, tap a different thinking modality, and just to change things up.
WODB has become a common acronym in classrooms for good reasons. (Actually, does it qualify as an acronym like NATO since I’ve never heard it pronounced as a word? Y’all are still saying Which One Doesn’t Belong, right?)
Take this first one I see on the site. (I added the numbers 14.)
I do my homework first, in the order that the shapes come to my brain:
 #2 doesn’t belong because it’s the only nontriangle.
 #4 doesn’t belong because it’s the only shaded shape.
 #1 doesn’t belong because it’s the only one with exactly one line of symmetry.
 #3 doesn’t belong because it’s the only obtuse triangle.
With students, I ask them to give me a blank grid and get ready to draw in each box as they listen to my clues. I tell them to make quick sketches as they may need to make changes when they hear new clues. I can give them the clues in any order I choose. But, we’ll stick with the order above.
 #2 doesn’t belong because it’s the only nontriangle.
A possible sketch:
 #4 doesn’t belong because it’s the only shaded shape.
 #1 doesn’t belong because it’s the only one with exactly one line of symmetry.
 #3 doesn’t belong because it’s the only obtuse triangle.
Students can then share their sketches and critique each other’s work. The reveal is fantastically fun.
Notice that if the first thing that came to my brain was “#3 doesn’t belong because it’s the only hexagon,” and I gave this clue to my students, then I may expect to see lots of different sketches.
Or, if I were the student, I’d wait for more clues.
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[Added 10/17/2020]
I meant to include a numerical WODB example because there are a lot of possible solutions, it’s always fun to see what the kids come up with. Here’s the first numerical one on the site. (I added the letters AD.)
I work on it first.
 D is the only nonsquare number.
 A is the only singledigit number.
 C is the only number divisible by 5.
 B is the only even number.
I give the students the above clues in the same order. However, students may not erase a number as they revise, they may only cross it off so that I may see what they had originally.
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Estimation 180 is another popular one. From the site’s Day 6:
Instead of asking students for an estimation, I ask:
One of the four numbers below is the correct number of almonds in the 1/4 cup pictured. Which one is it and why did you choose it? Which number do you believe is way off?

 8
 15
 28
 40
I find their reasoning and conversations are tighter this way — more focused. I’m also one of those people who dread having to guess at something, even with a visual clue. With younger students, I’d give them 3 choices instead of 4.
Open Middle is another wellloved routine. This one is filed under Grade 4, Equivalent Fractions. (I added the digits AG.)
Directions: Use the digits 1 to 9, at most one time each, to make three equivalent fractions.
I mark the digits 1 through 9 on red/yellow counters and put them into a baggie.
I reach into the bag and randomly pull one out. Say, I pull out a 5. I call on a student [randomly] and ask, “Which space (AG) can the number 5 not be in?”
There is a big difference between asking the above question versus, “Where do you think the number 5 goes?” The chance of answering this question correctly, if 5 is used at all, is 1 out of 7. The former question is much safer to tackle. This routine engages the whole class on one number at a time — we get deeper thinking when we can focus on one thing and while building on each other’s thinking. And I very much love it when students are given opportunities to honor and build on their classmates’ reasoning. After a few suggestions, a student might conclude that the number 5 can go into the discard pile. (It’s also common for students to use a number more than once or use a number not allowed, so the counters alleviate this mistake.)
Also, I need to share that this problem was posed in an online workshop I attended yesterday, and I didn’t even attempt it because these are my constant truths:
 Someone else will come up with the answer before I do.
 The answer will be revealed before I get to solve it, so no point in me ever working on it.
How many of our students also hold these truths? I understand this was a workshop for teachers and time is limited and sharing is good and all that. I’m just thinking about best practices with students though.
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