Today I took error analysis to a new level with my students.

I stumbled upon this video over the weekend, with the hope of finding a clip to review and reinforce Friday’s lesson on similar figures. After watching the clip (which erroneously presents triangles that are *not* similar) I decided to use the video to promote student discussion – and boy did it! As students watched the errors unfold, they started looking around the room at one another and naturally began discussing the problem at length. Not only did I accomplish the desired review, but I saw students defend mathematics and become emotionally involved in the process!

The morals of this story:

1) Even a bad video can be used to create good mathematical communication.

2) Don’t believe everything you see on the internet. 😉

Bummer – I made the mistake of contacting Math Planet before ripping their video. No more error analysis with a twist – and I need this for tomorrow’s lesson! Sad face.