I was looking for a problem to talk through with each of the kids this morning and this one fit the bill perfectly. It is a nice review problem for my older son and a nice way to (perhaps) introduce some new ideas to my younger son.

Also, the watching the two approaches to solving the problems is a nice illustration of the difference in approach that kids gain with a little experience (my older son is 2 years older than my younger son).

Here’s my older son’s approach to the problem. As this is more of a review problem for him, my goal is to have him carefully explain all of his steps:

Here’s my younger son’s approach. This is definitely not a review problem for him since he’s seen only a little bit of geometry. He knows a few basic ideas about angles and triangles, though, and he puts those ideas to use in his solution. The problem provided a nice opening for us to talk informally about angles and parallel lines, which was nice:

So, a luckily-timed tweet from Patrick Honner led to two nice conversations this morning. People sometimes look at me like I have four heads when I talk about all of the great math stuff that people share on Twitter, but here’s yet another example that led to some good conversations this morning!

Is the use of arrows a standard notation to indicate the lines are parallel? I hadn’t seen that before.