Talking through a tough geometry problem

We probably spent 30 minutes this morning talking through a pretty tough example problem in Art of Problem Solving’s Geometry book. For our movie project this morning I changed up the numbers and had him work through the problem again. It still gave him a little trouble, but he was about to get through it in about 10 minutes.

In the first piece we introduce the problem and he finds the relationships between the two sets of similar triangles in the problem. One of the big difficulties from this morning was dividing up the bottom part of the diagram into “y” and “100 – y”. As I wrote in a recent post, I’m really struggling to help him see how to label geometry problems in a way that helps get to the solution.

A concept I’m struggling to communicate


Next we moved on to solving the equations for x and y. Solving these two equations wasn’t really the main focus of the day, but intstead of just jumping right to the solution, I thought it would be good to talk about easy and hard ways to solve these equations.


I wish that I had a better sense of how to help my son get through some of these struggles. Going to keep trying lots of different ideas, though it feels a bit like I’m just throwing a bunch of spaghetti at the wall and hoping that something sticks . . . .

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