Shelley, thanks for the tip on the Math Grid Game - it was a huge hit. I named it "Magic Number" and actually drew the base ten cubes on the board above the "100 more", "100 less", etc. grid. The first person had to identify the number from the base ten cube picture. Also, I let the next student correct an error of a previous team member if they needed to when it was his/her turn. It was a great idea....and no prep. needed - just a white board and expo markers....that is so key.