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!

## Comments

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