Khan Academy videos a treasure for studying science, maths & finance online
Khan Academy from Salman Khan [not the bollywood actor] is a true treasure for students who would like to learn science, maths, and finance. There are over 1200+ FREE videos which take you through details of each of the subject areas. I wish this was around when I was in college and school.
Khan Academy is run by Salman Khan who gave up blooming career after graduating from Harvard Business school with MBA, to work full-time on teaching everyone the subjects that well everyone is scared off. He has a huge following and students from school and colleges tune in to learn and/or refresh their knowledge of these subjects.
Khan Academy website [LINK]