Clifford Swartz seems to be a paradox. He teaches physics and sings in a choir. He has written elementary textbooks and papers on high-energy particle physics. He is an agnostic who participates actively in his local church. Strangest of all, Swartz finds nothing strange in all of this. Indeed, he is completely at home combining these seemingly different activities in an effortless way.

For 29 years Swartz – my colleague as a professor at Stony Brook – was also the editor of The Physics Teacher, a publication that is aimed at those teaching introductory physics courses. A collection of his monthly editorials – wry and witty accounts of teaching physics at all educational levels – has recently been published as Cliff’s Nodes: Editorials from The Physics Teacher (Johns Hopkins University Press). With titles like “Physics, where the least action is” and “No-one kissed the physics teacher”, the columns instruct, amuse, plead, lecture, cajole, harangue, tell stories, relay facts and take up causes.

A node is an intersection point, and in these editorials Swartz links many apparently incompatible perspectives. Yet Swartz’s writing style blends them together seamlessly. Each column individually, and all taken together, offers valuable lessons about physics teaching.

Leading them out

Some of the columns address the content of physics lessons, discussing topics that can be converted into interesting classroom material, such as “blue” ice, plumb lines, materials that microwaves cannot warm, sounds produced by fizzy drinks bottles and so forth.

Other columns concern how to teach. Don’t treat students as little scientists, Swartz cautions. A physics teacher has to be part showman and has to lure students “into the tent” and supply further enticements to keep them there. “Physics instruction without demonstrations is like dinner without food,” Swartz writes. “Physics teachers are remembered for the afternoon everyone timed a ball dropping from the school roof, or the day the water spilled from the ripple tanks,” he notes elsewhere.

Yet content and execution cannot be separated. Swartz criticizes teaching methods that stress the need for students to memorize facts, formulas, and equations. But he also warns against patronizing students, expressing a dislike of methods that rely on hoopla, flash and dazzle, and the attempt to teach concepts without bothering to quantify them. Students visiting amusement parks and science museums, for example, should have to study what they will be doing in advance, arrive with real questions and follow up in the classroom, Swartz believes.

The word education, Swartz points out, comes from the Latin for “leading one out”. To lead students requires a firm grasp of where they stand, where you want them to go and how to attract them there. But the ground covered cannot be too great. Thus he advocates using familiar objects as physics props: Tinkertoys, nails, soap bubbles, rolling balls, toy cars, rubber bands and the like. With these simple elements – and inspired by curiosity and guided by quantification – students can be led into a great deal of physics. “If students can’t calculate the pressure exerted by the bed of nails, they’ve missed the point,” Swartz says.

Consider Swartz’s suggestions on what makes a good science project. Don’t try to make a giant leap beyond school work – no subatomic physics or string theory! Try studying a familiar but interesting phenomenon with more-complex-than-it-seems physics – rainbows, for instance. Not only is it an experimental challenge to keep a mist of rainbow-producing water from soaking the surroundings, but the physics is approachable, researchable and photographable, and the outcome pretty and satisfying, yielding a “high unlike anything else” response. When that happens, Swartz concludes, “No matter how the judging turns out, you’ve already won the science-project contest.”

Wonder and mystery, Swartz emphasizes time and again, are never far beneath the surface of familiar phenomena, easily accessible to students, and are essential to keeping their physics interests alive and fresh.

The critical point

One column in the book notes the giant leap that students must make between school and university classes, with Swartz urging that this discontinuity needs to be made smoother. He titles this particular column “Impedance matching”, referring to how when a signal crosses between two regions with vastly different loads, the load must be stepped down gradually or else the signal will be lost. (The horn of a trumpet, for example, does this when the signal – pressure pulses – made by the trumpeter’s lips travel down the bell into the open air, where the impedance is larger; if the bell were not there, most of the signal would not escape.)

Impedance matching is also an apt phrase for several other transitions that he talks about in physics education: between entertaining and instructing; curiosity and guided learning; and gaining pleasure from the world and coming to know it.

In fact Swartz’s columns taken as a whole might be described as impedance matching. It is a metaphor, after all, for the fact that the students remain human beings throughout their education – from having only a vague interest in the subject at the start to being specialists at the end. The transition is continuous and throughout requires teachers to appeal to, adapt and shape human traits. Swartz’s columns are about the importance of all the various small steps that need to take place in keeping students’ “signals” strong and stimulated.