One example is the procedure of drawing force, or free-body, diagrams. This method is commonly taught as a recommended first step when facing problems in which forces and Newton’s laws are at play. (Think of a block sliding down a slope under the influence of gravity and friction.) Of course, we emphasize the routine of drawing force diagrams because it’s a safe and effective strategy. But what if while stressing the usefulness of the procedure, we are inadvertently obstructing creative problem solving among the students?
This possibility is addressed in the paper When procedures discourage insight: epistemological consequences of prompting novice physics students to construct force diagrams. This well-written report describes an empirical study in which undergraduates are assigned two problems to be solved using Newton’s laws. The tasks are designed to allow for both a standard — but comparably cumbersome — solution, as well as a swifter shortcut approach. About half of the students — the ”prompt group” — are explicitly prompted to draw specific free-body diagrams in their solutions, while the control group is not.
The analysis shows that the prompt group was less likely to find or choose the shortcut approach. At the same time, students from both groups who did go for the shortcut option were more likely to arrive at the correct results. However, no difference was in the end found between the two groups when it came to getting the right answer. This apparent contradiction was explained by the fact that students in the prompt group tended to be more meticulous in constructing their diagrams, compensating for the fact that they less often went for the ”easier” shortcut solution.
What conclusions ought to be drawn here? Prompting a specific standard procedure seems to shrink students’ openness to clever alternatives, which otherwise save time and often is related to conceptual insights. On the other hand, students who get precise instructions seem to be more prone to getting the details right. (This is also supported by a correlation between course grades and choosing the standard approach; adopting procedures that are emphasized in courses is generally a good strategy.) Like the authors also point out: methods like diagram sketching are there because they facilitate problem solving. The challenge is rather how to teach valuable strategies and skills without causing the unwanted side effect of students avoiding creative alternative approaches. A simple suggestion: always add ”First, reflect on whether there are several ways to solve this problem!” to the problem-solving instructions.
Text: Emma Wikberg, Fysikum
