How often do professors teach the class?

<p>Is it a rare occasion that professors teach the class? Is it usually the TA who lectures?</p>

<p>I'd just like to get a good picture of how classes/discussions work. Thanks!</p>

<p>As far as my classes have been, professors teach the lectures, TAs the discussions. In lab classes, TAs are the bulk of the lab instructors, and professors teach maybe one hour a week.</p>