To that end, teachers use objects and games and challenge their first graders to think creatively about numbers. They may show children a group of objects and ask them, "How many ways can we make 6?" and together come up with 2 and 4, 3 and 3, 1 and 5, and 6 and 0. They will teach "fact families," a term for using the inverse relationship between addition and subtraction to solve problems. For example, 5, 4 and 9 is a fact family. If 5 plus 4 equals 9, then 9 take away 5 must equal 4.