I thought some of you (those who teach second grade) might enjoy my NUMBER RAINBOWS. The idea is that you connect two numbers with an arc if they add up to the particular number, such as 13.
Then, the child can use it as a reference when subtracting from 13 or when doing subtraction drill. You could first drill subtraction facts WITH the rainbow (such as 13 − 4, 13 − 7 etc.) and then without.
You would also ask the child to reproduce the rainbow - and color it, of course! These make for quite pretty math facts practice, don't you think!
I'm going to add these to my Add & Subtract 2-A book.