The TeachEngineering digital library provides teacher-tested, standards-basedengineering content for K-12 teachers to use in science and math classrooms.Engineering lessons connect real-world experiences with curricular contentalready taught in K-12 classrooms. Mapped to educational content standards,TeachEngineering's comprehensive curricula are hands-on, inexpensive, andrelevant to children's daily lives.

Site designed to help students with math skills.  Good for early levels through Algebra and Geometry.

Site for math practice in grades K-8.

Active site with several games to learn letters, shapes, and words.

This site, Physics Lessons.com iPhysics provide great physics lessons for students who can manipulate the data and record their observations.

"Interactives" provides educators and students with strategies, content, and activities that can enhance and improve students' skills in a variety of curricular areas.

The Khan Academy provides video lessons for students in a number of curricular areas.  This is a great resource for students that can be viewed on a desktop or laptop computer, iPads or iPods, or other tablet devices. 

Link to several free, fun, interactive, research-based science simulations developed from the PhET project at the University of Colorado at Boulder.

Useful site for learning letters and words.  Nice site for introducing early reading skills.

Wolfram Alpha is a search engine that can provide answers to most questions you type into the search window.  Includes examples and steps to solve mathematical equations through calculus.