Mean absolute deviation (MAD) is about calculating the average distance from the mean.

Below is a link to a video from our 8th Grade Math textbook that goes in to detail and explains how to calculate the MAD.
http://my.hrw.com/content/hmof/math/common/tools/videoplayer/index.html?contentSrc=16093/16093.xml

If you would like some additional practice please click on the link below and follow the instructions.
http://my.hrw.com/content/hmof/math/common/simulations/S8_15/index.html