There is nothing mean about this activity; unless, of course, you are talking about the average kind of mean. Conceptually the mean is much more than finding the sum of the values and dividing the quantity of values. In the activity Mean and Mean Absolute Deviation, students get to actively explore the concept of finding the mean by manipulating stacks of books. Once they have explored the concept they are then given the opportunity to practice finding the mean with the algorithm.
As the student’s progress through the activity they are then asked to use their prior knowledge of mean and absolute value to find the mean absolute deviation of a variety of data sets. This activity introduces students to finding the mean absolute deviation based on concepts they have already explored, and provides plenty of practice to support the introduction.