Aug 29, 2011

When a Mile Wide is Too Wide...

All physics teachers make choices concerning the depth and breadth of material they include in their courses. Physics First is a golden opportunity to establish a new paradigm of priorities for our students that is informed by recent developments in education research and PER.

In May of this past school year, I visited a public school in New Jersey that made the switch to Physics First about five years ago. The impetus for the switch initially came from the district superintendent, as a way to increase student scores on the state Biology test. (Though the state does not require students to pass the bio test to graduate, this particular test is held up as evidence that a school's science program is successful.) This reasoning is increasingly a driving force behind the switch to Physics First in many schools throughout New Jersey and beyond, as administrators notice how much better Juniors at PCB-sequenced schools (physics first, then chemistry, then biology) perform on a Biology test than Freshmen at BCP-sequenced schools. Though it's easy to question the merit of this rationale, the fact remains that Physics First is coming to more and more public schools for this reason. With it comes a great opportunity to teach an excellent introduction to the natural world and to the discipline of science.

The Physics First classes that I sat in on at this school were fairly typical of a traditional physics class: most sections were studying waves, and I saw diagrams of first, second, and third harmonics for standing waves on a string drawn on the whiteboard next to similar-looking diagrams for standing waves in open and closed tubes* (along with the ubiquitous and tautological λ=v/ƒ). An accelerated section was working under a different yearly sequence, and students were carrying out a lab on projectile motion in which they they attempted to place a target on the ground to predict where a projected ball would land. The teacher carried out the correct procedure for collecting the necessary data and making the necessary calculations, and then turned students loose to carry out these steps on their own.

A teacher new to the school revealed that a colleague who'd been teaching the Physics First class for a while already instructed him that the best way to teach physics to ninth graders was "a foot deep and a mile wide." This indicates a prioritization of content knowledge over critical thinking skills and, unfortunately, I have gotten the impression that this attitude is all too common among high school physics teachers.

A physics class taught in ninth grade has a great luxury over many physics classes taught in other grades in that standardized tests in physics for ninth graders have not (yet) gained popularity. An institution usually has to show indications that students have shown academic progress as a result of taking a Physics First course, but how the school chooses to measure these gains is often more flexible than for, say, a ninth grade Biology class. If a school wants to show that their Physics First class teaches students to think about science like a scientist, Lawson's Classroom Test of Scientific Reasoning can be used, and if a school prioritizes teaching students to internalize "Newtonian thinking," the most recent edition of the FCI (revised to be ninth-grader-friendly) can be used as well.

Given such an opportunity to emphasize scientific thinking and fundamental conceptual understanding, I'd love to think that "mile wide" breadth of content in Physics First would be our last concern. Does a student benefit from being exposed briefly to diagrams of both standing waves on strings and standing waves in tubes, when one diagram so often reinforces misconceptions about the other? Why would we ask our students to spend a lab period carrying out a prescribed procedure for solving a projectile motion problem when they could spend the same time designing and carrying out their own method of isolating variables and collecting data in a simple investigative experiment?Physics First is by no means a "silver bullet" solution to our science-teaching struggles . Rather, it is a golden opportunity: a chance to establish a new set of priorities for students that will impact their relationship to science throughout their lives, rather than asking them to perform the same old number crunching and regurgitation of bullet points.

*This has always frustrated me!! A very high level of abstract and sophisticated thinking is required to interpret the physical phenomenon that is represented by the "pressure vs. position" or "displacement vs. position" graphs (shown below) often presented during a study of standing waves. That these graphs look conveniently similar to the observable shape of a standing wave on a string only makes this more difficult to understand.
Here is an example of a conversation I had with a rather bright student while visiting another ninth grade class doing a lab on standing waves using tuning forks and glass tubes:

Me: So, what's going on in this tube?

Student: The air comes down the tube, bounces off the bottom, and then comes back up.

Me: How do you explain why these diagrams show two different lines for the air?Student: Those are the paths the air takes down the tube and then back, or... I guess that maybe the two prongs of the tuning fork would each make their own stream and then cross in the middle?
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