The Challenges of Teaching AP Physics

The mathematician Gilbert Strang once quipped that the good thing about being a mathematician is that you’re not trained in any particular discipline. You speak an interlingua which allows you to make contributions in diverse fields, like physics, economics, and linguistics. Strang then added that the bad thing about being a mathematician is that you’re not trained in any particular discipline. Whatever applied field you might be working in, you’re always playing catch-up.

Teaching math is like riding a bicycle for me. After a hiatus of over 30 years, I found it easy to pick it up again. Like most math PhDs, I taught a lot of math classes on the way to my degree. That’s where I learned that the most challenging students are the math phobic ones. As a teacher, my goal has always been to make math approachable, enjoyable, and fun for all my students, including the recalcitrant ones.

Teaching physics is not like riding a bicycle for me. For the first time, I began teaching AP physics a few months ago, and it’s been a lot of work. Why is that?

First, I wasn’t trained as a physicist. I took first year physics in college, and skipped directly to quantum mechanics and electrodynamics in grad school. I prepared for professional life by being steeped in mathematics, not physics, during my university years.

Second, I wasn’t trained to be a physics teacher. Yes, my general experience in teaching helps, as does my fluency in mathematics. However, I’m missing the academic rigor and teaching experiences that physics PhD students get on their way to becoming physicists in theoretical, applied, and academic settings.

Third, physics is presented and assessed very differently today than it used to be. Looking back at my old physics book by Halliday and Resnick, I see lots of words on the page, equations using calculus, a few sketches, and homework exercises involving straightforward calculations. Physics textbooks today like Giancoli contain explanatory text, sophisticated diagrams, full color images, conceptual exercises, and more sophisticated homework questions.

Fourth, there is greater variety in the high school physics classes taught these days. Individual schools offer multiple versions of AP physics courses. Each is tailored to one of the four different AP physics exams, which include algebra-based and calculus-based exams in Mechanics, and in Electricity and Magnetism.

Fifth, AP physics exams now include Free Response Questions (FRQs) instead of just multiple-choice questions. Multiple-choice standardized tests were the norm when I was in high school. More recently, the AP physics exams began including FRQs along with the multiple-choice questions. Because of the pandemic, the exams this year will be online, open book, and consist of only two FRQs to be answered in less than an hour (50 minutes for the algebra-based exams, 40 minutes for the calculus-based exams). Increased emphasis on FRQs makes teaching physics, and assessing a student’s acuity, radically different than the way I was taught and tested.

So what are these FRQs? FRQs ask conceptual problems, emphasizing qualitative over quantitative understanding. For example, one practice 2019 FRQ involves a uniform meterstick of mass M hanging from two spring scales, one located 20 cm from the left end of the meterstick, and the other located 30 cm from the right end of the meterstick. Part a asks the student to explain, without equations or calculations, which scale has a greater force reading and why. A correct answer to part a requires the student to identify the center of the meterstick as a “fulcrum” with no torque, and to consider the torque applied by each spring to the meterstick. Part b asks to student to calculate the reading in each scale, which requires the student to balance clockwise and counterclockwise torques. There are also parts c and d.

Fortuitously, I am trained as a mathematician. I am a jack-of-all-trades-and-master-of-none who has spent decades using my mathematical skills in diverse areas like linguistics, electrical engineering, and computer science. Teaching physics from a qualitative point of view is just a new challenge. By this time next year, I’ll be much better at it. You can count on it.