Annenberg Learner Interactive website that covers many content areas, including math, science, history and language arts. This site has many layers to it with lessons for upper elementary through high school, and a video library for teachers.
A great interactive site that introduces math, reading, writing, history and science concepts. It includes interactive quizzes and opportunities to answer questions throughout the videos. Brain pop jr. is for K-3.
Provides educational movies for K-3 students. Homework Help, leveled quizzes, games and activities for kids. Exceptional resource for teachers and homeschools.
This link to the Oxford English Dictionary is an invaluable resource for Middle School ELA and Secondary Ed English teachers. I can see it as a frequent "go-to" site for Student Researchers, providing more interesting content than a standard online dictionary. Because the OED is concerned with word origins, I believe it would be helpful in creating bridges with ELL students as well, giving them a chance to see the linguistic contributions their language has made to ours. Check out the link in the lower center column for teachers and students (resources and lesson plans).
This is an excellent site providing interactive text in a variety of subjects. I only checked out social studies, but there are various sections on math and science (some even in Spanish). Lessons are interactive and contain relevant images and great multimedia presentations. I highly recommend it.
Another cool thing about this site is that a teacher can set up an account and provide a custom HippoCampus page for his/her students. This can be helpful for all students, regardless of their abilities.