In the beginning you can simply just have them find two cards that equal that sum. To amp it up a bit change it by giving one point for each card that the player picks. For example, if the player rolls a 6 he could pick up a 5 and a 1 to earn two points, OR he could choose a 4, a 1, and another 1 to earn three points.
This game is played much the same way. For this game, you will need a 12 sided dot die. Each student will also need their own 6 sided dot die, a white board and a white board marker. To play a student will roll the 12 sided dot die to determine which sum they have to create problems for. Then, each player rolls their dot die. Player one looks at the dice and tries to find as many addends as possible to equal that sum. Since they get one point for each die that is used they try to decompose the number using multiple addends.