As a graduate student at UT, I've been a teaching assistant for 3 courses:

Sustaining a Planet - Freshman non-major earth science course focused on topics of sustainability such as the tragedy of the commons and alternative fuels.

Intro to Geology - Intro-level geology course with a significant lab component and fields trips led by the TA's.

Porous Media Flow - My advisor's graduate level course on modeling groundwater flow.