If you’ve been around here a while, you know concept sorts hold a special place in my math toolkit. There’s something powerful about asking students to categorize ideas — it pushes them to look for relationships, not just recall facts. And as a bonus? You’re hitting two of Marzano’s high-leverage strategies at once: cooperative learning and identifying similarities and differences.
As we began our work with geometry, I knew that classifying shapes would be tricky for some students. If research has shown solid evidence that categorizing and finding similarities and differences works—I’m all for it!
Here’s how I typically use concept sorts — though I’ll say upfront: there’s no single right way to do this. Let your students guide the process and don’t be afraid to adapt as you go. In this example, I started by grouping students into trios. I’m a big fan of groups of three — the dialogue tends to be richer, struggling students get more support, and there’s a built-in buffer if someone gets pulled out mid-activity.
Classifying Shapes Activity
For this sort, I gave each group a small piece of bulletin board paper for them to do their sort. For this sort, I made the decision to NOT give them their “headers” until later…stay tuned for why!
As my students sorted, I simply walked around and eavesdropped! It was a great time to listen for math language, to listen for any misconceptions, and to see who was feeling confident and who was not. After a few minutes of sorting, I pulled the students together to ask what categories they had picked. As you see, these sorts are as much for ME to learn about my students as they are for my students to learn about math!
Classifying Shapes: What did we notice?
So I brought the students to the whiteboard and we talked about HOW they decided to sort their cards into categories. Asking students to sort WITHOUT categories is definitely more complicated than giving them the headers, so you have to decide what you are trying to accomplish. I wanted to see if students already knew what polygons were based on their “math talk”. I learned the answer was “NOPE!”
This sort was designed to be an example/counterexample sort. I wanted the students to decide if the shape shown on the card was a polygon or not a polygon. In this case, I purposely filled the sort with shapes I thought might be tricky—and my theory proved to be correct!
Once we finished the sort, some clear misconceptions surfaced — and that’s exactly the point. Classifying shapes isn’t one-size-fits-all, and when we push students to do the harder thinking, we get a much better picture of where their understanding actually breaks down. That’s where the real teaching happens.
Great Math Discourse!
For this sort, I also decided to include a “not sure” category which I hoped would encourage students to have quality dialogue. If they could not come to agreement, they simply put the card in the “not sure” category. It prevented the really vocal ones from taking over! I gave the students a total of 15 minutes to do this job—and there were a few groups that did not get every card sorted. That’s okay. If I had given some groups 45 minutes, they may not have finished!
Up next? A gallery walk to check out what the other groups did!
Although actually DOING the sort is a valuable activity, gallery walks can add a whole new level of critique to the lesson! Sometimes I even have each trio take a post it note and cut it into three “tags”. They can “tag” up to three spots on other groups’ papers where they felt an error was made. After going over the key information I wanted the students to know, we talked about some of the trickier cards! These three really stumped some groups!
Getting students thinking!
We really stress the dialogue and thinking more than always worrying about who got them all right…these are experience-builders and all misconceptions DO get addressed through our lessons and instruction. The entire activity took us 25 minutes from start to finish and was a great kick-off for our unit. Before you read on–don’t miss this opportunity to try an algebraic thinking sort to start working concept sorts into YOUR planning. Click the image below or RIGHT HERE to grab it!
Check out some pics from another one of my classifying shapes sorts. For this one I used the “flag” technique which also prompted us to have an impromptu debate!
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| During our gallery walk on THIS sort, students placed “flags” on cards they thought might be out of place. Then the students returned to their “home” papers and studied the flagged cards. |
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| We had a handful of cards we needed to talk about! |
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| Which led to a HUGE debate about whether or not these two segments are intersecting. We had a GREAT discussion about the difference between segments, rays, and lines. |
So…hope you are intrigued enough to try some sorts on your own! It’s not hard to do–even make some samples of your own on index cards and try the sort as a whole class! If you are interested in checking out my geometry sorts, just click here or on the image below! Have a great week!
Or check out THIS POST for even more tips about using math sorts in your classroom!
If you want to explore more word problems in my TpT store, CLICK HERE to see the many different options!
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