He once taught an open to all freshman knot theory elective:

https://people.reed.edu/~ormsbyk/138/

I also remember taking a class on vector calculus from the same author... which detoured through rudimentary manifold theory and differential forms, and ended with a final week on de Rham cohomology and the Mayer-Vietoris theorem (on vector spaces, to be fair, and not modules in general.)

(And is a very fine K-theorist, too, if I say so myself.)