Below are some really fun websites that will help build your math skills.
    Cool Math Games.com
    This site has great strategy and skills-based games.
    It also has spelling and reading games.
    Math Playground
    This site gives your brain a real workout!
    It is especially good for practicing your multiplication facts
    which is extremely important for 5th grade.
    Cool Math 4 Kids
    This is a sister site to Cool Math Games.
    It contains some good brain benders and geometry puzzles.
    Click on 5th Grade for reinforcement skills.
    Sheppards Software
    Lots of fun games to play while reinforcing your math skills! 
    Tangrams help with spacial reasoning. Enjoy!