reach the interested people first (at least for _this_ talk.)
subexercise – evolving code
lots of students problems because of few resources frustrating to be a teacher and not be able to teach properly what's holding them back? you want to be able to teach better you want to be able to get the message across because the worst thing you can face each day is a classroom of bored, unmotivated, uninterested students who aren't learning and it's painful to check exams and see a lot of failing marks it hurts because you feel inadequate. you're not getting the job done.
if it's just a living if the results of their teaching are good other people will notice there is a direct benefit if they perform better in future classes
if we teach well the first time around, less need for reteaching good recommendation letters develop creativity and problem-solving (for teachers)