Specifically I am looking for short lectures (and quizzes) on specific topics.
(like Khan Academy offers)
Topics I am learning about include;
Intro logic-theory + set-theory
- Notation, negation, simplification, result of set operations)
- Relations, functions
Intro proofs
- By contradiction, induction, well-ordering
Intro graph theory
- Graph coloring (chromatic numbers), Eulerian paths, Eulerian circuit, Hamiltonian paths, Minimal spanning trees (Prim's and Kruskal's algorithms), shortest path computation
Intro combinatorics
- Permutations, combinations, inclusion-exclusion, binomial theorem
Best Answer
MIT has a portal where they put lots of courses on MANY subjects, and in a less informal way than Kan. Their material is really good, and you will probably find those topics in some of the courses there.
http://ocw.mit.edu/index.htm
EDIT: As mentioned in the comment by eccstartup coursera is another option, but with only a fraction of what you can find on MIT's opencourseware, but it still might have many different courses.