Well, we've finally finished up our units on double digit addition and subtraction with regrouping (a HUGE part of 2nd grade math) - YAY! Here is one of our math anchor charts:
Common core has actually made teaching regrouping just that much easier, as students are really delving deep and making their own understanding and connections. I love having "math talks" in the classroom and hearing students explain their thinking and reasoning. We are always discussing various strategies, and it's fun to see students hear other kids and how they may have solved a problem in a different way.
Anyway, we've started our unit on place value to 1,000, and our lesson yesterday was focused on having students find number patterns and skip count by 5's, 10's, and 100's. At the end of our lesson time, we played a little game. First, I had a 5's/10's/100's spinner on the board.
After having a kiddo come up and spin the spinner, I would make up a number pattern based on what the spinner showed. The students would then have to either continue the number pattern or find the missing number. They would write their answer in shaving cream on their desk, and then they'd discuss with a partner and justify their answers (love that my 2nd graders are using that word and know what it means!).
Such a simple activity I know, but it was motivating, fun, engaging, and it got the students talking and discussing. Sometimes we as teachers need to remember that it can be the simplest of things that can be the most effective. :-)