Math
From adding and subtracting up through geometry.
Websites

BrainFuse
You will need your library card for this online homework help for students in grades K12 offered daily from 2:00 p.m. to 11:00 p.m. Also includes practice tests, writing assistance, skills building and more.

CDN MathFrog
Fun resources and online games for Grades 4, 5 & 6

Find explanations of mathematical topics, practice problems, and challenging games organized by topic and grade level. Please note this is an American site and they may not be studying the same things you are.

Fractals: A Fractals Unit for Elementary and Middle School Students
This is written just for kids, to make it easy to understand fractals

An alphabetical and chronological index to biographies of mathematicians. A site for adults but pretty easy to use.

math.com  The World of Math Online
Practice your math skills from basic addition to calculus.

Click on the glossary to see lots of common mathematics terms with an animated example for most of them. There are math games too.

Check to see if your question has been answered already. If it hasn't, the Doctor will help!

This is a help resource for grades 48.

Designed to help students improve their math skills interactively with games, worksheets and flashcards.

Are you stuck on a math problem? This site allows you to find a problem that is similar to yours and helps you work through it.