Khan Academy

Khan Academy is an excellent site for both students and teachers. The non-profit Khan Academy website provides 10-20 minute videos on math, science, humanities, history, and a wide range of other topics. The site is continually expanded with new content videos. The site aims to cover the core standards, and they have a team of  teachers, tutors, and professors, who questions and peer review one another's content. Some lessons, such as math, have practice exercises to complete to determine skill mastery. The information is accurate and presented in small clips that are understandable. The videos offer tutorials available to all students. Most videos have closed captioning. http://www.khanacademy.org/