From the website my 10 year old daughter uses at school (I actually use it quite frequently when I forget the basics-which is surprisingly often considering how many math courses I took in HS and College!):

To Find the Median place the numbers you are given in value order and find the middle number. 

Look at these numbers. 

3, 7, 5, 13, 20, 23, 39, 23, 40, 23, 14, 12, 56, 23, 29 

If we put these nubers in order we have; 

3, 5, 7, 12, 13, 14, 20, 23, 23, 23, 23, 29, 39, 40, 56 

There are fifteen nubers. Our middle number will be the eighth number. 

3, 5, 7, 12, 13, 14, 20, 23, 23, 23, 23, 29, 39, 40, 56 

The median value of this set of numbers is 23.

If there are an even amount of numbers things are slightly different. In that case we need to find the middle pair of numbers, add them together and divide by two. Sounds complex. Follow the example. 


3, 7, 5, 13, 20, 25, 39, 23, 40, 21, 14, 12, 56, 23, 29, 32 
There are now sixteen numbers and the numbers have changed. 

3, 5, 7, 12, 13, 14, 20, 21, 23, 23, 25, 29, 32, 39, 40, 56 

In this example the middle numbers are 21 and 23. 

21 + 23 = 44 
44 ÷ 2 = 22 

The median in this example is 22. 

More at:
http://www.mathsisfun.com/median.html