Subtraction on the Train

There are many advantages to introducing addition and subtraction on the trains. Students can find the answer to addition and subtraction problems without having to be able to write numbers. The teacher does not have to explain or teach regrouping, because the regrouping happens implicitly when making good trains. Also, depending on the students’ level of understanding, they can take advantage of groups of ten, or they can add and subtract blocks one at a time.

	Let’s start with the problem 45 - 18. We start by making a train of 45.
	Now, we must remove 18 blocks and see what remains.
	We are left with the answer, 27. Notice that we do not need to discuss regrouping. All that students needed to know was how to count out 45, and then know how to count and remove 18 to get the answer.
	Students can count the 18 blocks that they need to remove from the train of 45 individually.
	Or, they can take off a full car (10 blocks) and 8 more single blocks. This is faster than the previous way of counting the 18 blocks. Students can use this method when they become comfortable with thinking about groups of ten.