Subtraction Algorithms

The key to solving any operation begins with an understanding of the number sense for that operation. Beginning subtraction is challenging for students, but then throw in regrouping, and a whole new challenge arises. Then add zeros, and more confusion arrives.

Our goal is two-fold. One is to get students to be able to subtract using the standard algorithm. The other is for that algorithm to make sense to them. That is why students struggle when they come to zeros in a problem. They can perform the algorithm because they know the steps, but they don't have the understanding of what those steps represent.

Following are 6 short videos, each one shows a method of subtraction. They are all based on different approaches to an understanding of what subtraction is. Remember, not all students approach a concept with the same understanding. Number 6 is probably the most difficult for us, because we do not approach subtraction from this understanding. But this is what many Hispanic students have been taught, if they went to school in Mexico prior to arriving in the states. (They use dots to indicate adding to a place value, where I crossed out the numbers to make it more concrete.)

Subtraction of Integers