What a kid learning math sometimes looks like: triangle inequality edition

Had a delightful time listening to my younger son talk through this triangle inequality problem this morning. It is fun for me to hear how a kid thinks about a fairly abstract concept like this one.

He had lots of nice ideas. Some probably helped him move closer to the solution and some didn’t, but he was always asking questions. I thought about breaking the first video into pieces but it didn’t seem like breaking up the natural flow of ideas made sense for this project.

One thing that surprised me was that finding the shortest side of the triangle didn’t seem to present a lot of difficulty, but finding the longest side was much harder for him.

Another surprise to me was that he initially thought that the triangle with the longest side would be a right triangle.


After we finished up with the problem, I thought it would be interesting for him to see the triangles. I think actually seeing the triangles helps drive some of the triangle inequality ideas home, and I loved “that’s a pretty cool triangle”


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