If you are stumped, visit one of the many websites such as those listed at the
Internet Public Library's KidSpace website. (This website is maintained by the University of Michigan and is an excellent site of all sorts of information). 

Be careful that you find ideas.  Don’t copy someone else’s experiment.  The goal is to create your own experiment. Other sites include those listed below.

All Science Fair Projects

AOL Science Fair Projects

Cyber-Fair Resources

Discovery School Science Fair Central

HomeworkSpot: Science Fair Project Center

IPL Kidspace: Science Fair Resource Guide

Math Ideas for Science Fair Projects

Mid-Columbia Science & Engineering Fair

Neuroscience Projects for Kids

The Original Science Fair Blueprints

School Science Fair Projects

 

Science Buddies

Science Club Projects and Experiments

Science Fair Central

Science Fair Idea Exchange

Science Fair Theme Page

Science Toy Maker

Science Wizards

Super Science Fair Projects

USDA Agricultural Research

Research Sources

Ask A Scientist

How Stuff Works