Teach Subtraction

How to Teach Subtraction So That It Makes Sense

In this article, I’ll discuss how to teach subtraction.  Subtraction is basically the complement to addition.  Once a child understands addition, there’s just a small step to understanding subtraction.  This is true for children learning 5-2 as well as children working on two and three digit subtraction.  Like addition, there is a traditional way that children are first taught subtraction and there are several more intuitive methods.  I’ll just go over the way I taught my daughter.

Subtraction without Regrouping

In this section, I’ll discuss how to teach subtraction without regrouping or renaming. Traditionally, teachers teach students two-digit subtraction by having them start in the ones column and then the tens column.  For example, what is the answer to 59 minus 43?  First, 9 minus 3 is 6.  Then, 5 minus 4 is 1.

I taught my daughter to start from the tens column.  In the above example, she would have said 59 minus 40 which is 19.  Then, 19 minus 3 is 16.  Initially, she was only able to do  two digit and three digit subtraction this way.  Recently, she surprised me by showing me the traditional way to do the subtraction.  She completely understood what happens in the ones and tens columns.

Subtraction with Regrouping

This section is about how to teach subtraction with regrouping or renaming.  Traditionally, teachers teach students two-digit subtraction by having them start in the ones column.  If the subtraction doesn’t work, students borrow 10 from the tens column.  For example, what is the answer to 81 minus 37? In the ones column, 1 minus 7 doesn’t work.  However, if we borrow 10 from the tens column then the subtraction is 11 minus 7 which is 4.  In the tens column, 7 minus 4 is 3.

My daughter however would have said, 81 minus 30 is 51.  Then, 51 – 7 is 44.  When I asked her how she got to 44 she explains that 51 minus 1 gets her to 50 and 50 minus 6 gets her to 44.  This method relies a lot on a understanding all of numbers that add up to 10.

How to Teach Subtraction with Games

At our house, we use a game similar to Chutes and Ladders, but we call it the Addition and Subtraction Treasure Trail. In this game, I lay out a number of flash cards (usually 10) in a snake like pattern on the floor. I make the flash cards so that I’m sure she can answer the math question. The answer is on the back of the card, and she can check herself. Every few cards I put a treat on the card. These treats can be toys or snacks. Needless to say, I never have to motivate her to do this game. I try to use it toward the end of the week when she’s starting to get a little tired. She does the math using the method above, and she doesn’t need to write anything down to get to the right answer.

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