Red & Black
Manipulatives and More
Red and black chips are often used to model addition and subtraction of integers. A red chip represents -1 and a black chip represents +1.
Addition is modeled by combining collections of chips. A red chip and a black chip "cancel" each other, so that any collection of chips with an equal number of reds and blacks represents the number 0. Experiment a little by modeling each of these addition problems.
Subtraction is modeled by taking away chips. You will frequently have to add 0 chips (i.e. an equal number of red and black chips) in order to have enough of one kind to take away. Try these problems.