Are lab exercises worthless? If they try to reinforce concepts, maybe so.

2 minute read

An essay by Natasha Holmes and Carl Wieman in Physics Today recounts their experiences designing introductory physics labs: “Introductory physics labs: We can do better”.

I’m linking to this because of their counter-intuitive research finding: Introductory physics labs that reinforce lecture content don’t actually help any students learn physics concepts better.

As Holmes and Wieman describe, one good explanation is that lab exercises have been too distilled by instructors, leaving no room for independent thinking.

The only thinking the students said they did in structured and content-focused labs (the kind in our study of nine courses) was in analyzing data and checking whether it was feasible to finish the lab in time. Although the finding may seem surprising at first, if you break down the elements of a typical lab activity, you realize that all the decision making involved in doing experimental physics is done for the students in advance. The relevant equations and principles are laid out in the preamble; students are told what value they should get for a particular measurement or given the equation to predict that value; they are told what data to collect and how to collect them; and often they are even told which buttons to press on the equipment to produce the desired output.

Laboratory units can be irreplaceable for learning experimental methods, how to design experiments, how to increase the sensitivity and accuracy of measurements. But teaching those skills requires a basic change in design from most laboratories.

I’ve followed Wieman’s research for many years. He is a Nobel-prize-winning physicist who has turned much of his effort toward improving the teaching and learning of physics by undergraduate students. In my experience, many of his educational suggestions—for example, getting away from lectures and toward conversations and interaction—are common sense for teachers in the humanities and social sciences, but novel for teachers in the physical sciences.

Still, when it comes to this research on laboratory effectiveness, I pay close attention.

Exploded skull image
This isn't my laboratory, but we do have some exploded skulls like this one. Photo by Hannah Gibbs on Unsplash.

Laboratory experiences are very important to the way I teach my introductory biological anthropology courses. I have not designed them with the intention of reinforcing lecture components. This is because the laboratories enable hands-on experiences with bones and casts, which I think is the most effective way to teach these subjects. That means I cover evolution concepts in lecture, but not the specifics of bone anatomy.

The greatest overlap of material from both lecture and laboratory components happens with human evolution, where students are learning species and concepts related to their evolution in lecture, and studying casts in the laboratory. In recent semesters, laboratories are not having the effect I would like to see.

The challenges in my labs are very much like those described by Holmes and Wieman. There is always a time crunch, because laboratory sections are only an hour long. One way to enable students to think and design their own experiments is to set up inquiry-based assignments that extend over several weeks.

This has been one of our most successful and popular approaches. But the students still require a lot of instruction and guidance, and I think we can do even better.