Using stories and elevators to subtract

Home

Chat

Blogs

Collection

Directory

Home : 2001 : October : 14

Using stories and elevators to subtract
By Louanne

When I introduce subtracting with zeros, I turn it into a story. For example, with the problem 701 - 286: We begin by looking at 1-6; it can't be done. So the number 1 goes to his next door neighbor, the zero, and asks
to borrow 1. But zero says, "I don't have any, but I'll check with my neighbor." Zero goes to her neighbor 7, who happily gives one to zero. 7 loses 1 and becomes 6. 0 adds one right in front, so she becomes 10. Then 1 can borrow from 0, who is now really 10. 10 becomes 9, and 1 becomes 11 after putting the borrowed 1 right in front.
Then we go to 9-8, which can be done; then

6-2, which also can be done without regrouping. So all the neighbors are happy!

It's kind of corny, but the students are able to visualize going next door and getting something, so it's another way to learn for those who are not "math smart."

The Everyday Math Program has lots of neat ways to teach kids how to subtract, other than the traditional way. They are really good, especially for those students who just can't do the regrouping way without making errors. My favorite method is what I call the Elevator Method. I begin by telling the students my "elevator story." When you go into the hospital to have some surgery, you climb into the elevator and head UP to the surgery floor. You're pretty nervous, so this is a NEGATIVE THING. GOING UP IS NEGATIVE. However, when you get out of the hospital, you climb into the elevator and head DOWN. You're happy that the surgery went well and you are feeling POSITIVE. GOING DOWN IS POSITIVE. Now let's subtract with the problem 807 - 294. Write the problem down with the 294 under the 807. Don't look at individual numbers, but look at place values. We'll start with the hundreds column. We have 8 hundreds and 2 hundreds. 800 - 200 = 600. Write that down under the problem. Put a PLUS in front of it, because we subtracted going DOWN, and GOING DOWN IS POSITIVE. Now look at the tens column. We have 0 tens and 9 tens. 90 - 0 = 90. Write that down under the 600, putting a MINUS in front of it, because we subtracted going UP, and GOING UP IS NEGATIVE. Now look at the ones column. We have 4 ones and 7 ones. 7-4=3. Write that down under the 90, putting a MINUS in front of it, because we subtracted going UP, and GOING UP IS NEGATIVE. Now look at what we wrote down: +600, -90, -3. 600-90=510 (mental math, counting by tens backward if needed). 510-3=507. 507 is the answer. No regrouping necessary, and students can learn to do this really, really quickly!
Wow! I hope that helps!