The #1 Math Discourse Activity



Have you ever been ridiculously excited to try something in your classroom after attending a conference? Back in 2015 I went to the National Council of Teachers of Mathematics (NCTM) annual conference where I attended a session about an incredible, quick, engaging activity to use in my intervention math class to increase discourse in math. I eagerly tried the math discourse activity with my students the very next week and was blown away by how engaged they were, how thoughtful they were, and how much participation I was able to get (especially from the students who sometimes ditched my class, but were actually there that day… do you have those students too?).


The strategy was called “Which One Doesn’t Belong?” Have you heard of it?



How It Works

As you can see in the image above, Which One Doesn’t Belong? is made up of 4 boxes. The prompt to students is simply, “Which One Doesn’t Belong?” and students need to explain why one of the boxes doesn’t belong in that image set.


For example…


y = x doesn’t belong because it’s the only one with just an x

y = 4 doesn’t belong because it’s the only one without an x

y = x - 4 doesn’t belong because it’s the only one with a negative y-intercept

y = 4x doesn’t belong because it’s the only one with a slope > 1


What other ideas did you think of?


The most important thing to do when making or facilitating Which One Doesn’t Belong? is to understand that the point is that students explain their reasoning, not search for a correct answer. It isn’t, “which one is correct?” it’s “Which One Doesn’t Belong?” It’s helpful if you give one pretty obvious answer so that it remains a low barrier to entry task and truly encourages participation from all of your students. It’s a great warm up activity to do in just the first 5 minutes of class each day that will give everyone in your class a quick math win!


Why It’s Amazing

This is such a powerful strategy because it has infinite correct answers… in math class! It also has a low barrier to entry which makes this a perfect activity to engage all students, especially students with learning disabilities in math, math intervention students, and english language learners. You will be amazed at the math discourse that follows.


During remote learning, Which One Doesn’t Belong? has been BY FAR the most popular strategy used from my workshops with my clients. And when I observe the teachers I support, wWhich One Doesn’t Belong? is BY FAR the strategy I see teachers using most to start their math class with strong engagement. By simply posting an image set, giving students the math discourse sentence starter of, “Which One Doesn’t Belong?” and then asking students to type their reasoning into the chat, you’ll be amazed at the math discourse this remote learning math activity can bring into your classroom.


How To Launch WODB With Your Students

The first time you launch this strategy to your students, I highly encourage you to try it with something non math related, just so students get familiar with the process and activity structure. If you teach students with learning disabilities in math or intervention math students, learning both a new activity structure and math can be overwhelming and nerve wracking for them. By introducing the structure with something non math related, students with math anxiety will feel more welcome to participate. You could try something like logos or superheroes, for example.


If you’re like me and love a good seasonal themed activity, you can check out my secondary appropriate holiday themed which one doesn’t belong slide pack that comes with five pre-made which one doesn’t belong slides ready to use in your classroom whether you’re in-person or remote. No prep. No printing. Just display and watch the conversations spark, even if you’re remote - it’s a great way to get students using the chat feature during remote learning!




Getting To Incredible Math Discourse

Once your students have gotten the hang of the structure you can use this strategy with any kind of mathematics. Seriously. You can check out my linear functions which one doesn’t belong? slide pack to access 8 pre-made, no prep, Which One Doesn’t Belong? presentation slides complete with student sentence stems and a word wall as an accommodation for students with special needs! If you're looking for a math discourse activity, math discourse questions, or math discourse sentence stems, this activity is it! The slide pack comes with facilitation instructions for in-person and remote math classrooms.




I cannot say it enough… Which One Doesn’t Belong? is THE BEST way to increase math discourse in your classroom and is one of the most engaging remote learning math activities I could possibly share with you.


If you try Which One Doesn’t Belong? in your classroom, let me know over on Instagram! I’d love to see how you use it in your classroom to increase math discourse!


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