Median in the Middle

Lesson Plan - Get It!

Audio:

The median is the middle number in a set of data.

The median is the number that is halfway into the data set. To remember the median, think of the middle child. In the example above, the middle child's age would be the number in the middle of the set. Take a look at how to figure out the median age of the Martin family's children.

To find the median:

1. Arrange the data in order from least to greatest [3, 4, 7, 11, 14].
2. Count the "number of" numbers in the data set.
3. If there is an odd number of items, then the median is the middle number [3, 4, 7, 11, 14].
4. The middle age, or median, is 7.

However, sometimes there will be an even number of items in the data set. That means that there will be an "even number" of numbers. When this happens, find the middle two numbers, then find the value that is halfway between them. This is easily done by adding them together and dividing by two.

Here's an example:

What is the median of the numbers 4, 2, 11, 6, 2, 7?

Step 1 Arrange the data in order from least to greatest: [2, 2, 4, 6, 7, 11].

Step 2 Count the "number of" numbers in the data set. There are 6 numbers in this data set.

Step 3 Find the two middle numbers, then find the value halfway between those two numbers: [2, 2, 4, 6, 7, 11].

4 and 6 are the two middle numbers. Notice how there are two numbers before them (2 and 2) and two numbers at the end (7 and 11). It doesn't matter that some numbers are repeated in the list. This is just a part of the data.

Step 4 To find the value between two numbers, add the numbers together and divide by 2: (4 + 6 = 10 and 10 ÷ 2 = 5).

The median value is 5.

Discuss with a parent or teacher:

1. How do you find the median of a set if there is an odd number of values?
2. How do you find the median of a set if there is an even number of values?
3. Explain what "median" means in terms of a data set.

Now that you are familiar with how to find the median, move to the Got It? section to practice finding the median.