Lectures were originally spoken text. Then the lecturers got famous and started publishing their text as books. Text books. Now we have lecturers who often lect

Lectures were originally spoken text. Then the lecturers got famous and started publishing their text as books. Text books. Now we have lecturers who often lecture from those words written by someone else. The best teachers I've known spend an inordinate amount of time writing out their original lesson plans. It's still text-based even if there are bells and whistles.