Education Development Center
Making Mathematics: Mentored Research Projects
After pairing professional mathematicians with groups of students, wonderful activities emerged. There are projects on this site, and use them in your own classroom.
National Council of Teachers of Mathematics
The Math Forum: Math Ideas for Science Fair Projects
Math Forum provides a list of possible math science fair topics with links to each topic to get an idea of what will be studied and suggested questions to answer. This site also contains links to teacher discussions on Math Fairs.