<p>I go to a small LAC and you couldn’t just sneak into most classes because the prof will look at you and ask who you are (classes are small). There are a few big classes where they wouldn’t know. However, I don’t think you’d get a lot out of a single lecture, and it’s quite impractical to hang around a college and sneak into the same class every week for a whole semester. Anyway, it’s called “auditing” and if you want to do it legally, you can check with various colleges for their policies.</p>
<p>Not many people care if you sit in on lectures, it’s not like you’ll be getting credit for it. That’s what you pay for! I had a teacher who let people sit in everyday to get a feel for the class before deciding to take it because it was a tough course.</p>
<p>a lot of schools offer free seminars that are open to the public…</p>