The popular video-sharing website has recently gained further praise, as more and more videos detailing subjects such as math, physics, sciences and biology are starting to get posted on-line by specialists or by people who have a gift of explaining fairly complex notions very easily. Students who flunk these subjects in class now turn to YouTube for comprehensive lessons, which, they say, help them better understand what they are being taught in class.

Psychologists say that learning on-line can have a very positive effect on the mind of the students, as they can start watching the videos whenever they feel like it, and when they are ready to focus on the issue at hand entirely. When going to class in the morning, it's pretty difficult for some to concentrate on complicated calculus if it's 8 o'clock in the morning.

Also, because the videos are streamed on-line, the students can rewind and follow an explanation several times, a thing that they cannot do in class, either because they are afraid of being laughed at, or because the teachers don't know how to explain it even if they go over a concept several times. Most teachers only know one way of explaining a notion, and if the students don't understand it, that's tough luck.

Professors say that watching these videos shouldn't be the only way children learn new information. They say that double-checking the information they watch on-line with the textbook is probably the best method for teenagers to ensure that they've understood a concept correctly. "It may seem like a small point but it lays a foundation for later problems. That's the strength and the weakness of this. In an eight-minute video, you can only do so much," says Walter Secada, who is an education professor at the University of Miami.

Overall, users who watch instructional videos on YouTube post comments that praise the author of the video, saying that the explanation they provided was very easy to understand. Some of those who post the educational material say that they already receive e-mails from around the world, in which people ask them the solution to a specific problem, or request a presentation for a certain topic. One of them even says that he aims at creating an on-line university, where people could get help on any topic they want.