I always thought that the purpose of a lecture was to pass information from the lecturers notes to the studants notes, without passing through the minds of either of them!!!!!
Seriously though you must a good lecturer to hold them in rapt attention for that long. Normaly I drift off after abZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ ZZZ ..............