Classes that dont have a lot of people who sign up

<p>Do the breadth requirement courses usually have a lot of room? I assume E 10 and 7 have a huge number of ppl as practically all engineering majors need to take it. Am I right? I’ll probably still do chem 112a as i love organic chem. also, what is phase one and two? When do prefrosh sign up for courses?</p>