If you're a teacher, what's your ambition? It's got to be better to watch your students chase their dreams than, when they come to tell the story of their success, be remembered as the person who said they couldn't do it.
The equation-filled blackboard is one of the most reliable props of academia, not just in cartoons and movies, but in real life. You know a scientific discussion is taking a turn for the serious when the protagonists head to the board. Walking into a colleague's office, a glance at the scrawled notes on their board gives you a taste of their current research preoccupations and teaching commitments; wobbly chalk drawings along the bottom edge are a pretty good sign that the office's owner has a small child in their life.