Fraboom is a fun, educational interactive museum which is targeted to elementary school children. The site includes several activities, including games, cartoons, interactive books and even live classes conducted by a teacher.
All activities are educational but are also very appealing to chidren by including animations, storylines and sound effects. I would certainly add this to the list of sites for your students and own children to explore.
Most of the content on the site is free but you can purchase a Gold membership for $5.99/month which will give you access to all of the content and activities. The site is flash based so will not likely work on devices such as the Ipad.
You can get more information by watching these videos: