<p>To the OP,</p>
<p>Your class will be taught by a professor. Your professor will have posted office hours when you can drop in and see him/her with follow-up questions or just to get to know them. You will have breakout review sessions run by TAs who are (typically) graduate students. The purpose of the breakout review sessions is to allow the students to clear up any confusions or follow-on questions from the lecture. If you are still struggling with the material, you will need to seek out a tutor. </p>
<p>This approach, with minor alterations, is standard operating procedure at USC, UCLA, Harvard, MIT, Berkeley, Michigan and is in fact the way of doing things at just about every school with the word “University” in its name. If you don’t like/want to deal with TAs your option is to attend a small LAC where professors are more directly involved thanks to smaller class sizes.</p>
<p>Will a TA occasionally lead a lecture? Yes. But usually it will be in an area that they have particular research expertise. </p>
<p>Are all professors great teachers? Are all TAs bad teachers? No. Like all human endeavors, there is a range of ability and execution. The TA discussion is the inverse of the “We have more Nobel Laureates than you do” argument. In certain situations your TA may do a better job explaining a concept than the professor. Just because you have a great level of expertise in a subject doesn’t mean you have the first clue on how to teach it. Just look at the great athletes who have gone on to become spectacularly horrible coaches (e.g., Isaiah Thomas).</p>
<p>At universities TAs exist at most every level of class taught. As you get into higher level classes and class size gets smaller there will be fewer TAs. But in all likelihood the TA sitting in on a seminar section will be nearly as well versed on the subject as the professor leading the class. TAs are professors in training the same way a Resident Surgeon at a teaching hospital is ‘in-training’. The only difference is you’re awake when dealing with a TA, you’re asleep and may never know if the lead surgeon did your operation or the resident.</p>