If you're looking for some fun ways to review exponents, here is a list of websites that have games involving exponent practice.
http://www.mathgametime.com/games/otter-rush-exponents-game
http://www.math-play.com/exponent-game.html (this is for those looking for a real challenge)
http://www.ixl.com/math/grade-8/multiplication-with-exponents
http://www.ixl.com/math/grade-8/division-with-exponents
http://www.ixl.com/math/grade-8/multiplication-and-division-with-exponents
http://www.ixl.com/math/grade-8/power-rule
http://www.mathgametime.com/games/otter-rush-exponents-game
http://www.math-play.com/exponent-game.html (this is for those looking for a real challenge)
http://www.ixl.com/math/grade-8/multiplication-with-exponents
http://www.ixl.com/math/grade-8/division-with-exponents
http://www.ixl.com/math/grade-8/multiplication-and-division-with-exponents
http://www.ixl.com/math/grade-8/power-rule