This educational website is safe for all ages, although it targets students from high school to graduate school. Much of the content is unavailable anywhere else and very useful, with an emphasis on interactivity to increase interest.
Math IQ Games
July 26, 2011 -- Submitted by Aramis, a teenager from Seattle, WA, who is not affiliated with the site.
I like Math IQ games for the following reasons: First of all, all games are fun to play and target a specific math skill necessary for math curriculum or standardized test. Almost all games are free after registration, which is needed to keep history of scores to monitor progress over time. Highly recommended over general brain games.
Mastermind
February 15, 2011 -- Submitted by Ryan, a reader from Sydney Australia, who is affiliated with the site.
A simple code cracking game that is good for developing or teaching logical thinking.
