Inquiry Stylee: A Hyperbolically Oversimplified Way to Teach Physics
I had a conversation with my wife and mother-in-law over a near-plasma-hot bowl of soup. I believe it was a corn chowder with shrimp.
I asked anyone if they wanted an ice cube in order to lessen the blistering of epithelial tissues that usually accompanies soup, but the question quickly turned to how many ice cubes were needed, because, obviously, the only thing worse than hospitalizingly hot soup, is tepid soup.
We began to talk about the things that mattered. Things like: the temperature of the soup, how much soup, whether someone’s was chunkier than an others, how cold the ice cubes were (to some, it isn’t obvious that not all ice cubes are
created chilled equally), and so on.
The physics implications of this discussion hit me so hard that I ended up hijacking (again) the entire dinner conservation and redirected it to be about teaching science. Ancillary question, why do teachers think everyone cares about every little nuance of teaching? I KNOW I DO.
Here’s the AHOWTP model:
- Introduce/stumble upon a situation that people actually care about that screams a question or questions.
- Make a list of all the things that might depend.
- Send the students off to do experiments to determine whether alleged things do or do not depend. One suspect per group.
- Each group reports out to the class (i.e. whiteboard), and then an equation/relation/law/principle can be built with unit analysis guiding the way.
- Done. Go eat a sandwich; I recommend grilled asparagus/kale (depending on the season) with Dijon mustard, homemade mayo, some prosciutto, and ripe tomatoes on grilled potato bread. Exclude the tomatoes, if they aren’t ripe and local.
There’s so much learning and thinking wrapped up in the word “depend.” The students will need to design a controlled, legit experiment. They’ll need to analyze messy data for real or fake relationships. They’ll need to undergo the scrutiny of their peers. Ok, I’m welling up. I need to stop and just give an example.
Here’s how this goes with a unit on friction in physics
- Friction does well with crappy introductions (i.e. “Hey kids, chapter 7 is on friction, so you should, um, like, give a shit about that now…”), but I prefer to do it with sleds, because it’s always winter here. (I live in Narnia). The questions come freely: How much energy does friction waste? Does roughness really matter, because, like, rubber is weird and frction-y?
- Students go nuts with this: Weight, surface area, smoothness, roughness, speed, acceleration, color, temperature, and so on.
- We then use the patented Cornally investigation-o-tron to build investigations. In other words, write me a grant telling me what you want to change, and what you want to measure. As a class we tend to come to a consensus on what we want to measure. Student-built experiments can often be summed-up with a naked graph:
- Each group of students reports out whether their variable had some kind of effect on the stopping distance of the sled. We record the relationship (squared, linear, exponential, whatever) and the variables on the board with a giant:
Unit analysis and numerator/denominator analysis is then done to see if we can build something useful.
A few interesting things have fallen out of this pattern. We often don’t get good enough results to measure things like the one-half on the kinetic energy equation or in the accelerated kinematics equation. The question then becomes, what’s our range, and should it even be some magic integer or nice number like 2 or half, or 3? This leads to even more experiments.
Also, the Socratic dialogue is really fun here, because it’s one of the only times that Socratic dialogue doesn’t translate to students as “this guy is annoying and full of himself.” We really have to get everyone on the same intellectual boat before we can throw away surface area, or put all our money on weight.
A final note, this is built on the Modeling Physics technique of asking students “what is measurable?” I love it that ModPhys puts a premium on getting students to think about reliable experiment design. I worry that ModPhys for some reason believes everyone cares about Tumble Buggies, although it’s much more fun when you put a match on one and a balloon full of butane on the other front end of colliding buggies (go outside).