2. Khan Academy
Home to more than 3,000 videos on subjects ranging from SAT prep to cosmology, art history to calculus, Khan Academy is a great place to learn.
Detailed courses are broken into smaller sections of text or videos for ease of learning that fits into your schedule, and all are self-paced so you can spend as much or as little time with the subject as you like.
You can also leave comments or ask questions if you want more information or if something isn’t clear in the lessons.