This site provides hundreds of practice problems and would be good for the Algebra 1 – Part 1 student.
This is a good primary site. It has a ton of stuff to look at. Fun activities, flashcards, awards, etc…
Explanations on just about any kind of math can be found at this site. For example, geometry will link you to 43 different proofs of the Pythagorean theorem.
On this site, you can find a new brain teaser every Wednesday in math. There are also links to Reading/Language Arts, Social Studies, and Science.
On this site, you can play math baseball. Questions can range from easy to super hard.
This site will show step-by-step explanations for actual homework problems in math textbooks, and will range from Middle School to Calculus.
How Stuff Works
This site favors the sciences, electronics, home, auto, etc…and is great at explaining how things work.
This site contains lesson plans, and interactive math tools ranging from Pre-K to 12 th grade.
Joy of Pi
This site is exclusively about pi.
This site provides homework help and tutoring for students. Subjects range from Basic Math to Calculus.
This site contains K-12 math puzzles, problems of the week, and a student center that can link you to different tutorial sites.
This site is dedicated to studying the powers of ten.
This site concentrates on Algebra. It has many lessons for teachers and helpful guides for students.
You can find a lot of quizzes, games and activities at this site.
This is a good site for a variety of academic areas. Math, Science, History, Astrology, etc…