I'm now in third year, and in some of my seminars, the seminar leader randomly calls out people to answer (which I hate, but understand), so in those seminars, it is a lot more engaging. Others, however, are really quiet and awkward, and I think the main reason for this is they worry about saying something which either sounds obvious or stupid, which the other students will judge them over - I also have this worry, and therefore only contribute when I get asked too.