Which website is best for?

[Happy]

studying online . If I wanna learn a little extra from the board syllabus which site is best ? For physics and chemistry . Supposethere's a topic in my text book . The explanation is not clear enough or there's something more to know which site will provide that much informations .
And I'm not good at math . So if you could suggest something .
Thank you in advance . Your answers will help of a lot

[Jake]

http://khanacademy.org/ has innovative instruction on a variety of topics.