Interactive/Virtual Math Manipulatives - Great Site!
The Utah State University has created a website of interactive/virtual math manipulatives. They broke the manipulatives down by grade level groupings as well as topic area. There are 20 different areas to choose from and many different tools for each area.
http://nlvm.usu.edu/en/nav/vlibrary.html K-8 Interactive Math Web Site
An interactive math Web site with interactive practice, explanation, and challenging games for math concepts grades kindergarten through eighth. many free, but some are for sale on a CD.
Lesson ideas and helpful information. Some free interactive activities. Covers many different age levels. Down side, it has advertising on the site which can be distracting.
http://www.coolmath4kids.com Get Smarter in Math and Science
There are educational games for these subjects as well as a student page with helpful information. There is also a Challenge where students enter general information about them and then take a test. The score of that test is then compared to similar students around world. Scores can be compared to other countries by scrolling over that country's flag.
Tutorials on identifying, renaming, comparing, and manipulating fractions. There are also some games that all relate to fractions.
http://www.visualfractions.com/index.htm Mini programs all dealing with math.
This site has 279 mini programs (Java Applets) all dealing with math. They range from middle school level through college. Some of these are very complex and will need more instructions as the students work on them.
http://www.ies.co.jp/math/java Math lesson plans and NCTM Standards
This site is created with the NCTMs in mind. This site has lesson plans, the NCTM standards, interactive tools, and additional Web resources for learning different math skills.
http://www.mathsnet.net/cruncher/index.html Math interactive activities
This math site has many interactive activities and games involving area, patterns, place value, number lines and number value.