the best clicker question I used last term

Context: a “conceptual physics” course with 50+ students enrolled, and 40-45 in attendance any given day. (I don’t take attendance in any way, and offer no credit of any kind for clicker question responses. I do not want to frame the interaction as “figure out what the instructor is looking for”. Despite that, I typically get 80-90% attendance rates, and near-100% answering rates on clicker questions.)

Timing: towards the close of a unit on magnetism, after gravitation and electrostatics have been taught. (No guarantees that they’ve been learned, though.)

Question: If you were a superhero, which power would you rather have?

1. Change the mass of things.
2. Change the charge of things.
3. Change the magnetization of things.

Why is this a great question?

For one thing, it’s pretty obvious that even if the instructor might have a preferred answer (which he didn’t), there’s no “correct” answer in an absolute sense. So, students can relax a little and explore what they actually think.

I generally run this one without a small-group discussion phase before the poll. When the poll has been taken and students begin voicing their choices and reasons in the whole-class discussion phase, it rapidly becomes clear that there are many different ways to think about the question.

And then the shift happens. Students stop thinking about their goal as “come up with the most correct thing to say” (or worse, “come up with the thing the instructor wants to hear”), and start thinking about it as “come up with the most clever thing to say”. The interaction has been reframed. Score!

Somebody picks “mass” so that they could make a bullet harmless by dropping its mass to near-zero, or so they could throw a pebble and then increase its mass hugely so that it would punch through a wall. Someone else says “Wait a minute, if you increased its mass, would its velocity stay the same, or would its velocity become tiny so that its momentum was conserved?” Everyone looks at me, and I shrug and say “I guess it depends on how this superpower works, eh?” I couldn’t care less how it would work, but I’m very happy that the connection between mass, inertia, and momentum has been articulated. Score!

Someone else says they picked “charge” because they could make lightning zap things. I ask if anyone picked “charge” for a different reason, and someone else says that if they could control charge, they could make things attract or repel, which means they could make things (including themselves) levitate or fly. “Mass affects gravity, which is only for attracting; charge affects the electric force, which can attract or repel.” Score!

Then another student piggybacks on that, saying “But wait, the magnetic force can make things twist and turn as well as attract or repel. Wouldn’t that be more useful?” Someone replies “Huh?”, and a short clarification dialog ensues. I smile. Then a student asks whether the power means that non-magnetic things could be made magnetic, or only that magnetic things could be made more or less magnetic, or have their polarities switched, or what. I shrug again, happy that the distinction has been voiced. Score!

Then one student who’s been quiet all along speaks up. She says “I think I want to control charge, because that’s what brain cells use to communicate, so I could alter people’s thoughts. Maybe I could alter computer programs, too.” Eyes widen throughout the room. Score!

In the resulting silence, I innocently inquire whether she’d need to be able to sense all the charge patterns flowing around—and even harder, interpret them—to make that power useful. She looks nonplussed, and then says “Well, at least I could scramble someone’s head pretty well, maybe give them amnesia!” Laughter.

The actual discussion doesn’t flow quite this smoothly and efficiently, of course; a fair number of less interesting, or less defensible, or less comprehensible assertions are made, and I do a little prompting and steering to bring out some of these points. Nevertheless, I’ve accomplished three very important tasks: We’ve compared and contrasted gravity, the electrostatic force, and the magnetic force, and the roles that mass, charge, and magnetism play within those; I’ve engaged the students in creative, open-ended thinking to apply abstract physics ideas to real-world (okay, comic-book-world) things; and I’ve gotten the students to enjoy physics class. Triple score!

This one question nicely instantiates all four principles of Technology-Enhanced Formative Assessment (TEFA):

• Motivate and focus student learning with question-driven instruction (QDI);
• Develop students’ understanding and scientific fluency with dialogical discourse (DD);
• Inform and adjust teaching and learning decisions with formative assessment (FA); and
• Help students develop metacognitive skills and cooperate in the learning process with meta-level communication (MLC).

BTW, my inspiration for this question was a biology question by Cathy Wanat of Northampton (MA) High School (since retired). It showed a photograph of a long buffet table loaded with different food dishes, with lines of people moving along both sides as they added food to their plates. The question was “Which of the following is most like this picture?”, and the answer choices were various parts of the digestive system: mouth, esophagus, stomach, small intestine, etc. She said the resulting class discussion was mind-blowing. Thanks, Cathy!