# The Real Life of Mental Math, by guest blogger Dawn Morris

by Dawn Morris, M.A. of Moms Inspire Learning

## How does math relate to real life? Let me count the ways.

- You’re ordering pizza, but how many slices, or pies do you need? You not only need to know how many people, and how many slices each will eat, but how much it will cost.
- You have 3 errands to do, but you only have half an hour. Can you complete all 3, or not? Which ones can be done in the least amount of time?
- There are 11 cookies left, but 5 children would like to share them. How many cookies does each child get?

When you really think about it, each of us uses math every single day. We usually aren’t using a calculator or writing down computations, though. A lot of what we need to do involves **mental math**. In other words, we need to be able to calculate math quickly in our heads.

Mental math often involves the use of **estimation**. For example, if you’re ordering pizza for 7 people, you can get a general idea of how many slices each person will eat, but you won’t know for sure until people actually eat it. So, if you estimate that each person will eat 2 slices, you’ll need 14 slices. If there are 8 slices in each pie, you’ll need 2. You might be left with two extra slices, or you might end up with more. It’s better to have too much than too little!

This type of mental math is rather advanced for children in the primary grades, but that doesn’t mean that you can’t explain your thinking process, and have them help you with the addition.

For young children, let’s go back to the cookie example. If you have 11 cookies on the table, and there are five children, you can just ask how many they think they will each get. You can then have them hand them out (like dealing cards) to verify their answer. A child who has learned fractions may say 2 1/5 cookies, but most will probably round down to 2. Rounding is a form of estimation!

You can also tie estimation in with place value. For example, if you print up a blank hundreds chart , you can have them count out ten small items, like buttons, and then fill in 90 more to make 100. If they see what 10 items looks like, and then 100, it’ll be easier for them to estimate larger numbers of that item. They could even practice skip counting by 10’s.

A great book to help with these fun activities is Bruce Goldstone’s *Great Estimations*. The author uses photographs of different quantities of items to help children learn different estimation strategies. He uses real objects, like jelly beans, cherries, pennies, macaroni, and buttons, which you can then take out and have your child practice with at home! While a 5 year old might want to sort the items, or group them by 10s, an older child might want to compare and estimate larger numbers of objects.

Another great resource, which is recommended for children who are 7 years old and up, is Betcha, by Stuart J. Murphy. Two boys find out that a toy store is having a contest. If they guess the correct number of jelly beans in the jar, they will win two free tickets to an All-Star Game. On their way to the store, they practice their estimation skills in a variety of ways. I won’t give away what happens; but I will tell you that at the end of the book, there are some wonderful follow-up activities that you can do with your child.

No matter how old your children might be, they will have a lot of fun estimating how many real life objects are all around them every day. It’s not only a great way to practice mental math and estimation, but they’ll realize that math really is all around them.

We do so many mental math calculations every day without even realizing it. If we point them out to our children, they’ll see that math really does relate to real life. As important as it is to read every day, it’s also important to seek out the math! It really is everywhere. A simple change in mindset can help us find it.

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