<p>I’ve taken a good number of larger classes including ones on the Chem, Bio, and Psych departments. In my experience, most professors break down into review sessions (some optional, some mandatory) with TAs leading the sessions. However, they have all been very receptive to students seeking extra help during office hours, so you can still get the one-on-one contact. </p>
<p>I’d also like to point out that for the majority of my classes, the TAs have been fellow undergrads. It’s great to have that contact and know that I too have the opportunity to TA for my fellow classmates.</p>