NeoK12 Educational videos, lessons, quizzes, games and puzzles on sciences, social studies and other core subjects; also has a number of interactive diagrams to label online ..
Fuel Our Future Free resources for science, technology, engineering and math (STEM). The site is searchable by elementary, middle school, or high school grade levels. For each grade level, there is a video section, virtual lab (where science is explained with an interactive activity), and brainteasers.
Mathtrain.TV Short, student-created videos explaining basic math topics, such as prime factorization, finding the better buy with unit price, percents, and others.
Snag Learning Documentaries produced by well-known educational resources, including PBS and National Geographic; searchable by subject and grade level; includes discussion questions for each video.