Today I learned that the least effective means of teaching is lecture. I also learned that the human attention span is somewhere between 12 and 15 minutes.
I learned this during a 3 1/2 hour lecture, with no breaks.
The lecturer read the powerpoint to us. The principal sat in the back of the auditorium to make sure no one left. He actually had a bathroom pass. One. You had to take the pass and bring it back to go to the bathroom.
Quality professional development.