Geometry Sort

I personally love sorting. There is just something about putting things where they belong. Neatly.

But it's also a great teaching tool. I have to give all credit to my instructional coach because I never would have thought of this on my own.

I'm supposed to be teaching a unit on triangles: isosceles triangle theorem, triangle sum, inequality, altitude, median, midsegment, and bisectors. I haven't taught all of them before so I didn't have much to go on. I searched all my usual places and couldn't find much either.

As luck would have it, I happened on this pdf and on page 4 and a lesson was born.

I copied the cards on hot pink card stock, cut them out, and put them in an envelope. Students worked together in pairs, one envelope per pair.

The only instruction I gave them was to sort them into piles. I was extremely unhelpful and would not answer any questions except to say "Do whatever you think." I gave them about three minutes, walking around to see and hear what they were thinking.

Then I asked them how many piles they had. They answered with 3, 4, or 5. I told them they should have exactly 5 piles. So they sifted through their piles and resorted.

Again, I'm offering no assistance.

Next I passed out their notes for the day. At the top there were 5 empty boxes with labels. I asked them to match their piles to the labels and place them in each box.

Again, not a word.

I then held up one card to the doc camera and asked what they labeled it. We went through each of the piles and from the feedback I was getting, it seemed that every group got them right.

We had good discussion about how they sorted, why they picked that label, what did the markings mean, how was each pile different, and so on. I had them move the piles and then draw the diagram into each box. Collect the envelopes, and continue on with our notes.

I love this because it was a lot more meaningful than me saying, "This is a median. Draw it." It always takes more time than you would expect but the students are so engaged. It's a low risk, non threatening way to get every student involved, prompt good discussions, and definitely kick up the higher order thinking. Anyone can sort. From there, you can take the activity anywhere you want to go.

Every time I do a sorting activity, I just smile so big inside because the kids think they are getting away with not doing math, without noticing that I'm the one getting away with not doing math.

I think this is a strategy I need to hit on more often because it helps me remember why I chose to teach math in the first place and lowers my frustration with the whole when will we ever use this issue.

Plus a little hot pink never hurt anybody.


  1. Hmm...this activity looks familiar. Can I ask where exactly you got it from?

  2. I agree with Margie. This looks like a freebie that is posted on Teachers Pay Teachers as well as on Pinterest. If it is, you need to give the original author credit, or you are breaking the copyright law.

  3. This comment has been removed by the author.

  4. The PDF that you happened to find is located on TpT and can be found here: http://www.teacherspayteachers.com/Product/Line-Segments-of-Triangle-Sort-Flash-Cards-Memory-Game

    You should have given the author of this game her due credit and directed your readers to the her link at TpT.

    Just because and item is FREE doesn't mean it isn't copyrighted by the author.

  5. Anyone reading this blog post should know that the material posted to the box account was AUTHORED by someone else, and is COPYRIGHTED. It was posted to box without the author's permission. You will see the copyright at the bottom of each page.

    If you would like to obtain the FREE resource in the proper and PROFESSIONAL way, please use the link Dee provided above.

    To the blog owner, I am really surprised someone working on a Master's Degree would not be aware posting someone else's work without their permission is not only unprofessional but against copyright laws???

  6. Thanks for all of your polite comments!

    Since you clearly read my post, you must have noticed that I never took credit for creating the resource myself. I downloaded it a long time ago (considering that this post was written over a year ago) and no longer had the original link, so I uploaded it from my box account.

    If I was trying to take credit for the resource, I would have cut off the copyright that is at the bottom of ever page as you so nicely pointed out.

    I am very happy to give credit to the original author and I appreciate you saving me time by finding the link for me.

    Thank you for approaching me in such a proper and PROFESSIONAL way.

  7. Thanks for bringing this activity to my attention and sharing how you adapted it in your classroom. I will definately pass this on. :)

    I was trying to develop an open ended explore on these topics to help students discover concurrency and median segment ratios. Was hoping to motivate some proving.
    Can you or any other readers of your blog point me to more explorations on this topic?

    1. Check out this search engine: http://www.fishing4tech.com/mtbos.html

      I typed in concurrency and got several quality lessons.

  8. This looks awesome! Thanks for sharing your ideas. : )