The Jefferson Lab is a research lab in Virginia that also has some great, free Science and Math Resources for students and educators.
The site has Teacher Resources with activities, lesson plans, projects, worksheets, and more. There are sections for students with homework help, videos, puzzles and resources. There are science and math games, flash cards, videos, puzzles, and science demonstration videos.
The site also has online practice tests for science, math and technology based on Virginia standards. The student can select the number of questions, topics (math including algebra and geometry, science including biology and chemistry, and technology) and then get started. It tells the student if they are correct or not so the student can learn from it.
This is a great, free resource for Science and Math students and educators.