Science Fair
- Experiment Central: a six volume eBook that you can read on your computer. This has experiments in full detail with resources and difficulty levels.
- Science Fair Project Resource Guide: How to select project, resources, articles and advice
- Library of Congress Science Fair Resources
General Science
Math
- Khan Academy is a good source of Video Tutorials on many subjects, especially math at all levels.
- Excel Easy offers a fully-illustrated Excel tutorial + 300 examples.