It sure is warm in here, said Harlan. It sure is, said Blurtso. That’s because a greenhouse, said Alex, turns solar energy into thermal energy, which in turn creates a convection process. What? said Blurtso. Solar energy, said Alex, passes through the glass and gets absorbed by the ground and plants. The plants convert the sun’s short wave infrared rays into long wave infrared rays—into heat energy—which can’t escape the glass. Because the air is trapped, the warm air near the ground rises and the cool air near the ceiling falls, turning the greenhouse into a convection oven which forces the air to become warmer and warmer with each rise and fall. A convection oven? Said Blurtso. Exactly, said Alex. Does that work on a small scale? said Blurtso. Of course it does, said Alex. So I could bake a pumpkin pie, said Blurtso, in a miniature greenhouse?
What are you doing? said Harlan. I’m grazing, said Blurtso, I’ve got to get this grass under control. What about school? said Harlan. School will have to wait, said Blurtso. O.k., said Harlan, I’ll take notes for you… is there anything you need? No, said Blurtso, I’ve got plenty to eat, and the snow will quench my thirst. O.k., said Harlan, I’ll tell the professor why you’re absent. Thanks, said Blurtso.
Hello, said the professor. Hello, said Blurtso. Your roommate told me why you missed class, said the professor. I’m sorry, said Blurtso, but this greenhouse is my responsibility. Your responsibility? said the professor. Yes, said Blurtso, it was entrusted to me, and I’ve neglected it too long. I admire your sense of duty, said the professor, but your grade will suffer. That is a price, said Blurtso, I’m prepared to pay. On the other hand, said the professor, I might be able to give you service-learning credit. Service-learning credit? said Blurtso. Yes, said the professor, for doing something that benefits the community. How does this benefit the community? Your greenhouse, said the professor, could be a model for self-sustainability in Cambridge. A model? said Blurtso. Yes, said the professor, but you’d have to be willing to talk to people about what you’re doing and why you’re doing it. I’m doing it, said Blurtso, because I waited too long, and I can’t wait any longer. Exactly, said the professor.