Order of Operations in the Real World

I was shopping at my local Target the other day with my niece (who is 7 years old) and she wanted to buy a few items. So naturally, as her math teacher aunt, I had her calculate the total.  I realized that we were using the order of operations in our real lives without even realizing it!

How do you teach Orders of Operations?

Often times, I feel like order of operation is taught only in the confines of math class. We don’t see how it can translate to the our world. So often we teach it in distinct steps: First, you work the parenthesis, then the exponents, then multiply, then divide, then add, then subtract.  This can be quite confusing to students as they move up levels of math because while yes, we calculate what’s in inside the parenthesis first and calculate the exponents, but does multiplication always come before division? Does addition always come before subtraction?

What about in this example?  4/2 x 3 – 5 + 1

In this example, if you solved this problem working multiplication first, it wouldn’t work because you would end up with 4 divided 6. While we could use fractions, I hope you can see that have to remember to look at multiplication/division as a pair and addition/subtraction as a pair and work these operations from left to right.

Order of operations in the real world

So back to my niece and our Target trip a few days ago. We were back to school shopping and she wanted to buy 1 lunch box for $10, 3 packs of paper for $12 each, and 1 pairs of jeans for $18. The jeans are $5 off. If we were in math class, we may have written an equation, but in real life you think $12 times 3 = 36 so 36 + 10 = $46 for my paper and lunch box. Now my jeans are $5.00 off so $18-5 = 13 so 46 +13=59. (excluding tax). We just used Order of Operations!

If we used an equation, it could look like this 10 + 3 x 12 + 18 – 5 = ?. 

                                                                          10 + 36 + 18 – 5=?

                                                                              46 + 18 – 5 = $59

It’s easy to see we could easily make a mistake. If we were not following the order of operation rules, we might do this:                                                                                                                 10 + 3 x 12 + 18 – 5 = ?

                                                                                   13 x 12 + 18 – 5 = ?

                                                                                       156 + 18 – 5 = $169

                                                                       That almost 3 times our original amount! 

There are a lot of examples that you can use with your students. Back to school shopping is a great one, but you can also try going to eat at restaurants, calculating tips, splitting the bill. Did this spark anything some ideas for you?

Would you like some order of operations lesson plans? Download an entire chapter of lesson plans, including order of operations, from the Prealgebrateachers.com Community today!

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