In articulating our own ideas, we examine our understanding, capture knowledge and develop strategies with which to consider new knowledge. We make new links in our thinking which happens more readily than just through reading or listening and writing. Learning is co-operative and tutors can find out what goes on in students' heads through this feedback. They find out where there are gaps in understanding and what help students need that they can give. Learning is not just about what you know but about using what you know and seminars are an opportunity to practise this.
Real understanding means being actively involved and contributing.
Students are not expected to be experts, but they are expected to question, think about, consider, WHY things happened the way they did, WHAT influenced ways of thinking and to predict or suggest HOW things work or might turn out in the future. In this case, seminars would be no different from lectures. Taking notes is important, but examining ideas and discussing them makes for better understanding. Lectures are designed for the transfer of information but seminars give the opportunity to discuss it in more detail, to understand and question the information that you have been given. Think of them as a great opportunity to 'have a voice', not just be one of the crowd.