Teacher’s Assistant/Teaching Aide
Basically an older student helping teach the younger ones as a parttime job. Generally involves a lot of crappy work like supervising labwork, helping out with grading and answering the same question 18 times.
Can be real fun though and often you get deeper insight into the subject than just attending a class or gain valuable connections into the institute.
In my personal experience, it usually means doing 80% of the professor’s work for minimum wage pay so the $140k/yr prof can fuck off and go brown-nose the school Board of Trustees all term.
The Prof might be doing other research too, as universities aren’t just for teaching undergrads. He might be advancing science in his field