Students can do the activity by themselves or turn it into a game. Students use playing cards aces through 10. They flip over two cards. The highest becomes the sum. The other number becomes an addend. Then the student solves for the missing addend. Students can play against each other. The student that solves all four of his problems first (and correctly) is the winner of that round. I laminate the game board and students use a dry erase marker. This game makes for a very easy to prep center or activity. The Subtrahend Game is played in the same manner, except the biggest number becomes the first subtrahend.