<p>My son went in undeclared and had both huge and small classes. Every semester, without fail, he would have opportunities to have meaningful interactions with his professors. They would often occur as a result of him asking a question during or after class and then spending time discussing it with the profs. He also went to office hours once or twice, which I never thought he would do unless he needed something. The prof’s would end up talking to him for an hour or even longer. I should note that this happened in Humanities courses, which tend to encourage discussion. I think Berkeley is as small as you make it, both academically and socially.</p>