We played Double Compare in math.  In pairs, each student turns over 2 cards - they look at the 2 cards and decide which card has the biggest number.  They say the biggest number and count on the other card (example: 9 and 6 - say nine and count 6 more. 9, 10, 11, 12, 13, 14, 15).  the parntner with the highest number gets all the cards.
We are adding by counting on from the highest number.