There are so many ways we see and use integers in the real world. We even add and subtract integers all the time, though we might not realize it. So even though teaching how to add & subtract integers might sound scary to both teacher and student, there are actually ways to introduce this in real and meaningful ways. This post includes a real life lesson you can use to add & subtract integers and help kids see the “rules” before you actually teach integer rules.
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Teaching Integer Operations Through Problem Solving
To begin introducing integers, I prefer to start with real world examples. This can include common things like temperature, being above or below sea level, or other ideas that may or may not be familiar to students such as golf scores (above or below par).
In this lesson, the focus is on money, and balancing your budget. In this example, kids will add & subtract integers as money is earned (through working) or lost (by buying things).
What’s great about this lesson is that kids will actually use integers in a meaningful context and will see integer rules play out (such as when you have a negative and subtract a positive you end up with a bigger negative).
In addition, kids will see the commutative property, so that no matter what order they include the transactions in their ledger, they will always end up with the same amount of money in the bank.
How to Add & Subtract Integers
When you’re ready to set up this lesson, begin by printing a tracking page for each student. You will want to print this front and back so that students have enough space to keep track of each line item in the budget.
Students will then need a set of word problem cards.
I suggest putting students in small groups, and having them go through the cards in a different order. In this case, you can print just one set per group.
Just be sure students are careful not to mix the cards up or lose track of what items they’ve already calculated.
You want them to see that at the end, they all end up with the same final balance.
You could also assign this work individually, which means each student will need a page of word problems.
Then they could go through them in order, without cutting the cards out.
If you do it this way, every student should have the same answers all the way through the assignment.
This might be helpful if you’d rather everyone complete it in the same order so you can discuss various steps and compare how they worked them out and how they wrote their equations.
Finally, you will need to give everyone a starting balance.
If the starting balance is $0, they will end the assignment with $277 in the bank.
If you start with money already, however, you will end with: (starting value) + $277. For instance, if the starting balance is $500, you will end with $777.
I hope this lesson provides a fun, real life math lesson for your students, and begins to build a foundation for how to work with integers.
Extension and Follow Up Questions
To follow up, you’ll want to discuss why all students ended up with the same final total (if they didn’t, have them go back through their work to check first).
You could also discuss this specific situation and ask, “How could Bob have saved more money?” or “What was the best/worst choice he made with his money?”
You could also challenge kids to compare specific problems that are similar and estimate which is better. For example, what is better for Bob, working 5 hours at $15 an hour or working 10 hours for $10 an hour?
After discussing ideas, estimations and strategies, work out each problem.
Finally, you can then discuss what they noticed about integers and as them to explain in their own words how to add negative numbers, or how to subtract negative numbers.
When you’re ready to explore the integer rules more specifically, you might like this lesson to add & subtract integers.
This shows what happens as you add & subtract integers using +/- tables.
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