Funbrain.Com
includes e-books and interactive games on several topics, including:

Math Baseball        Grammar Gorillas   The Plural Girls      Math Car Racing Proton Don

 Interactive Math
 the links listed on all  pages are interactive (unless otherwise noted)  and contain a wide variety of activities for the grades K - 12.

KiDS!
Games, activities and a ton of fun for NASA kids!
 
 National Geographic Kids
 includes interactive games featuring animals, geography and more

 NickJr. Com - Play to Learn
 online games and stories featuring characters from popular
 shows

 PBS Kids Go Games
 a large variety of games for various age levels
 featuring familiar characters from public broadcasting programs

 Scholastic.com  kids
 features games, contests and book-inspired online activities.
 

For additional links to educational children's sites, search the many local K - 12 school web sites.