For many middle-school children, math is a real challenge. It is at this age that the concepts begin to get more abstract, and work goes beyond "concrete" ideas like adding and subtracting. It's no surprise that at this age, math can become something the student avoids, or begins to dislike.
Great, fun and free math worksheets should be able to present a mathematical problem in different ways. Math is after all nothing more than a numeric expression of some of life's simplest questions:
How much money do I have left if I buy a soda? By the end of the week, how much of my daily allowance will I be able to save if I don't?
However, caution must be taken into account when review is repeatedly covered in your classroom. You do not want your students to become bored or frustrated with the repetition.