Please notice how students are using a bar diagram for word problems. The top of a bar diagram is the total and the bottom shows the parts.
When should we subtract?
1. When you have a total and one of the parts, you subtract to find the missing part.
2. When you are trying to find the difference between two numbers. For example, when the problem asks how many more, we subtract.
3. When you have an amount, and some of that amount went away.
Also notice how students can use a letter (we are using the letter n) for the missing number. They are also able to write an addition equation for subtraction problems and they can check their subtraction work by adding.
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