The Power of Pineapple
"What can I do to motivate my students?" I think to myself, as I hastily pack my things one morning before heading to school. "They talk in class, they fail my tests, and even if I broke down and started caning them like the other teachers, they still wouldn't care about physics."
Then suddenly, a revelation: "I'll tempt them with food!"
Bag packed and sandals strapped on, I leave my house—a two-room shop stall at the heart of a rural trading center in western Uganda—and walk over to the produce stands across the street. I pick out a juicy, medium-size pineapple and get the woman selling it to peel and quarter the pineapple for me. At 25 cents, it seems like a relatively small price to pay for classroom cooperation.
I arrive at school, pineapple in hand. My Senior Two (S.2) physics class sees me coming. As usual, whoever was supposed to teach the 8:00 - 9:20 block never showed up, giving the kids free reign to screw around outside. But playtime's over. It's 9:20 on the dot, which means everyone in a khaki green skirt or trousers—the S.2 uniform—should be seated at a desk for physics class. I walk towards the students hovering outside the S.2 classroom at a relaxed pace, a nonchalant lion stalking easy prey. My prey glance at the pineapple. Their mouths begin to water. But then they look at the lion that's carrying the pineapple, and they know it's time to run. Luckily for the lion, they run straight into the classroom. No chasing required this time.
I enter the classroom and wait until everyone's seated. Then, without a word, I take out one of the pineapple quarters and bite into it slowly. A little juice dribbles out of the corner of my mouth. I let out a long, deliberate "Mmmmmmmmmm" as I take my time enjoying the perfection of this fruit. My S.2's gaze longingly at the golden, glistening pineapple.
"Master, is it sweet?" one asks.
Before I answer the girl, I finish the slice, making sure to lick its juicy remains off of each finger to emphasize just how much she's missing out on.
"Yes," I say. "It's very sweet."
I then address the entire class. I explain that there are three slices of pineapple remaining. Coincidentally, there are three students seated at each desk. I'm sure there's at least one desk that's worthy of pineapple, but I'm not sure which desk it is.
"So," I say, "we'll have ourselves a little contest. Remember last time when we talked about swimming? About how your ears hurt when you dive deep underwater?" I get a few nods. The rest probably haven't ever gone swimming. "Well, that pain you feel is the water pressure acting on your eardrum, also known as the tympanic membrane. If too much pressure acts on it, the eardrum can rupture, or tear. And then you wouldn't be able to hear anything."
All very well and good, they're thinking, but what does this have to do with pineapple? "Scientists," I continue, "have found that the eardrum will almost certainly rupture if exposed to 100 kilopascals of pressure. For the rest of this pineapple, calculate how deep you would have to dive to rupture your eardrum. The density of water is 1 gram per cubic centimeter and gravitational acceleration is about 10 meteres per second squared. First desk with the right answer gets the pineapple. Go!"
At that moment, hell freezes over. My students are actually working! I pace the room like I usually do when I give in-class problems. Only this time, I don't need to play disciplinarian. Hands shoot up as I walk by, offering answers to my question. I look at the answers. I dismiss several lacking units of length. Some people are off by a factor of 1000. Others have copied numbers from a previous, unrelated physics problem. But finally, a group of boys gives me the correct answer of 10 meters. We have a winner! I present the boys the pineapple and return to the front of the class to put the solution on the board.
"But master, you give me that pineapple," a girl pleads, Bambi-eyed, head cocked to the side with her hands outstetched, expecting a reward.
"No. You didn't answer my question correctly. However, there's more pineapple where that came from..." I turn to the class and grin, "...if you answer some more questions."