Agree with MoN here. It's good to see the same concept/procedural tool from different angles.

One of the things missing from a lot of math instruction at lower levels is the idea of "checking" using an alternative method. While I realize that with arithmetic, automaticity is the eventual goal, the HABIT of using a secondary method to back up your conclusions is actually a good one. He won't keep using it here, and neither will classmates.

smile


Schrödinger's cat walks into a bar. And doesn't.