What use are lectures now that everything can be found online?

I have often wondered what students were actually learning when they were sitting in large classes listening to my lectures. I had also read that standard lectures are not an effective way for students to learn, Gibbs [1]. So, in 1997 I decided to try to find out: - why my students attended lectures - how useful they found lectures - what they learned from the lectures There is virtually no information on these questions in the literature that is specific to mathematics.