MIT OpenCourseWare
MIT OpenCourseWare is an offering of free college-level engineering-related course materials to the public.[1]
While many courses are provided, they vary widely in popularity and usefulness. The site lists a ranking of its most popular courses, which tend to be the ones providing solutions to the problems.
Some of the "courses", such as "8.962 General Relativity" as taught in Spring 2006, consist merely of a set of textbooks and problem sets without solutions, and no lectures.
The courses do suffer from some liberal bias. For example, its course on Microeconomics does not mention the important, Nobel-Prize-winning Coase Theorem (or any other specific economic theories or thinkers) anywhere in its syllabus,[2] and only mentions it in a narrow, understated manner in a lecture having the title "market failure" (a term never mentioned in the lecture).[3]