I retweet Scott's video talking about multiplication with his daughter. (He has lots of nice videos along these lines.)
/Explaining/ a trick is good math!
Which Marilyn responds to... (talk about fanboy). And we will be looking into this trick.
Links: Scott's post with his video, Brad's video, Marilyn's blog with her trick.
Since this wound up here, I thought I'd share how I subtract.
When I was in 2nd grade, Mrs. Schultz told us you can check subtraction by adding the result back. 6 year old mathchico thinks that if this is always correct, why don't we do that in the first place?
132 - 49? 3 plus 9 is 12 so 1+4 (now I'd say ten + forty) is 5, and 8 plus 5 is 13. Done, 83.
Over the years I've gotten in a lot of trouble for not borrowing.
Solved and checked, Mrs. Schultz!
Peace be to any teacher who had me in class, up to and including my advisor, Nigel Higson.
And Dan writes my signoff: