HowStuffWorks is an award winning educational website that will make you leave your School. However, please don't leave your school because it won't be giving you certificates currently.
This website is not a new one on the net and hadn't been silent since its establishment in 1998. Moreover it is also on TV; ya The Discovery Channel shows it.
What's great in this website is that you can find almost everything can think of.
Try searching something. If anyhow you don't get the answer you can always ask them (see the bottom right on the above picture). Click on the link and you can ask questions to the brain(they say). The answer comes pretty fast for a this huge website.
The must see website for you guys.