When people speak of a "middle" score they often think of what is known as the arithmetic mean or just mean, for short. This is what most people also refer to as the "average" of a set of scores. However, a strong case can be made for calling the median "average," too. Thus, we will try to avoid using the term "average," in order to be more precise and to avoid confusion.

It is quite possible that you are already familiar with this method of measuring the middle. When your English teacher determines your final grade for the semester, he or she probably uses the mean of all your homework, quiz, and test scores. You may have even taken the mean yourself in an effort to find out your grade before the report card.

If you are not familiar with the mean, don't worry. That's what these lessons are for... and after you learn about the mean, you'll be able to check up on your teacher to make certain you get the grades you deserve. But you'll never learn a thing if you don't continue to the next page.

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