The mean and the median

Ages 9 to 12 Read alone or together · about 25 minutes

Read together

The mean is the average. Add the numbers, then divide by how many there are.

The median is the middle number when they are in order.

Do it

1. Measure the height of five family members or the pages in five books.
2. Add them and divide by five to find the mean.
3. Put them in order and pick the middle to find the median.
4. Add one very large number. Which changes more, the mean or the median?

Talk about it

• What is the mean?
• Why does one big number change the mean more?

For the grown-up

Mean and median describe a set of numbers in different ways. An extreme value pulls the mean, and the median resists it. Be sensitive about comparing heights or weights of people.

Mark as done

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Where this comes from

• National Governors Association Center for Best Practices and Council of Chief State School Officers, Common Core State Standards for Mathematics (2010), standard 6.SP.A.3 and 6.SP.B.5c (mean and median)
• Moore, D. S., and McCabe, G. P., Introduction to the Practice of Statistics (W. H. Freeman, 2005)

Written with AI assistance and checked against the sources listed. Please read it before sharing it with a child.