The internet provides a great learning environment, and lots of sites offer collections of free videos that you can watch in order to teach yourself about various subjects. One excellent example, which has been mentioned a couple of times recently in our forums, is the Khan Academy. It hosts over 2000 short videos, instantly available for you to watch online within your browser for free.
The site is very much science-oriented, and covers subjects such as maths, algebra, physics, chemistry, finance and so on. Each video is short, concise, educational, and very easy to follow. The videos have already been viewed some 44 million times in total, and it's not hard to see why. Not only is the content great, but the titles are clearly laid out on a single page, ready for you to just click on any that you want to view.
Definitely worth checking out, especially if you're a student or you know someone who is.
The URL you need is www.khanacademy.org.
My thanks to reader Jay Jani for recommending this site.