Comparing three methods for teaching Newton’s third law

Although guided-inquiry methods for teaching introductory physics have been individually shown to be more effective at improving conceptual understanding than traditional lecture-style instruction, researchers in physics education have not studied differences among reform-based curricula in much detail. Several researchers have developed University of Washington–style tutorial materials, but the different curricula have not been compared against each other. Our study examines three tutorials designed to improve student understanding of Newton’s third law: the University of Washington’s Tutorials in Introductory Physics (TIP), the University of Maryland’s Activity-Based Tutorials (ABT), and the Open Source Tutorials (OST) also developed at the University of Maryland. Each tutorial was designed with different goals and agendas, and each employs different methods to help students understand the physics. We analyzed pretest and post-test data, including course examinations and data from the Force and Motion Conceptual Evaluation (FMCE). Using both FMCE and course data, we find that students using the OST version of the tutorial perform better than students using either of the other two.

Figure 1

Carts $A$ and $B$ are on a table as shown. A constant force is exerted on cart $A$ by the hand so that the carts speed up at a constant rate. Compare the magnitudes and directions of the force exerted on cart $B$ by cart $A$ with the force exerted on cart $A$ by cart $B$.

Figure 2

Cart $B$ is at rest on a table as shown. Cart $A$ approaches cart $B$ from the left and collides with cart $B$. Immediately after the collision, the two carts separate. Compare the magnitudes and directions of the force exerted on cart $B$ by cart $A$ with the force exerted on cart $A$ by cart $B$ while the carts are in contact.

Figure 3

FMCE data, overall N3 score. Comparisons of three curricula, with separate columns for normalized gain in the N3 cluster, improvement (fractional possible gain) in use of MDF, and improvement in use of ADF.

Figure 4

FMCE data, collision situations in N3. Comparisons of three curricula, with separate columns for normalized gain on collision questions, improvement (fractional possible gain) in use of MDF, and improvement in use of ADF.

Figure 5

FMCE data, pushing situations in N3. Comparisons of three curricula, with separate columns for normalized gain on pushing questions and improvement in use of ADF. Use of MDF is very rare in pushing situations, and only on pretests. Note that results are not statistically significant and are included for completeness only.