This set of I Have... Who Has... cards can be used to review the addition and subtraction of positive and negative rational numbers. The activity will engage all students in solving the problems.The set of cards can be divided into sets of 10, 15, 20, or 25 cards. So it can be used in a class with 15 students, 20 students, or 25 students. (Or some students can be given more than one card.) Each students gets a card and anyone can begin the activity by reading their Who Has ... All the rest of th