MIT OpenCourseWare makes teaching materials used in MIT undergraduate and graduate courses available on the web, free of charge, to any user anywhere in the world. It is not a degree-granting or credit-bearing initiative, but a large-scale, web-based publication of MIT course materials. Educators are encouraged to use materials for curriculum development, and self-learners may draw on materials for self-study or supplementary use, including learning resources specially developed for high school students.
OCW is online at http://ocw.mit.edu/.
What a great resource!
How fun! And fun learning is forever learning!