Developing model-making and model-breaking skills using direct measurement video-based activities

This study focuses on student development of two important laboratory skills in the context of introductory college-level physics. The first skill, which we call model making, is the ability to analyze a phenomenon in a way that produces a quantitative multimodal model. The second skill, which we call model breaking, is the ability to critically evaluate if the behavior of a system is consistent with a given model. This study involved 116 introductory physics students in four different sections, each taught by a different instructor. All of the students within a given class section participated in the same instruction (including labs) with the exception of five activities performed throughout the semester. For those five activities, each class section was split into two groups; one group was scaffolded to focus on model-making skills and the other was scaffolded to focus on model-breaking skills. Both conditions involved direct measurement videos. In some cases, students could vary important experimental parameters within the video like mass, frequency, and tension. Data collected at the end of the semester indicate that students in the model-making treatment group significantly outperformed the other group on the model-making skill despite the fact that both groups shared a common physical lab experience. Likewise, the model-breaking treatment group significantly outperformed the other group on the model-breaking skill. This is important because it shows that direct measurement video-based instruction can help students acquire science-process skills, which are critical for scientists, and which are a key part of current science education approaches such as the Next Generation Science Standards and the Advanced Placement Physics 1 course.

Figure 1

This video shows a wave moving down a large horizontal spring. Students can access interactive tools by selecting the Ruler and Stop Watch buttons on the bottom toolbar. Using the tools, they can measure the amplitude, frequency, wavelength, period, and speed of the wave. As indicated on the bottom toolbar the current video shows the lowest of five possible frequencies, the largest of five possible amplitudes, and the lowest of three possible tensions. By using the drop-down menus students can select different values for these parameters, which allows them to easily perform a range of experiments. For the model-making assessment (Appendix pp1), students in classes that had not studied wave phenomena were asked to determine the relationship between the wavelength and frequency of a wave. Successfully completing that task required students to design, execute, and analyze an experiment where the frequency of the wave was varied and the wavelength was measured (while holding the other parameters constant). You may use this online resource for free at the link in Ref. [35].

Figure 2

This graphic is a slightly modified version of a figure from Zwickl, Finkelstein, and Lewandowski’s paper on modeling [36]. The diagram does an excellent job of concisely representing the steps in the process of modeling in science. Within this framework, model breaking is represented as a sequence of steps that begins with Data (upper left) and ends at stage E. Note: for this work we did not emphasize the intermediate step “measurement model” which appears in that sequence of steps. Our conception of model-making (going from data to a physical system model) did not appear as a transition in the original graph, so the diagram was modified by the addition of the yellow “model-making” arrow. It should be noted that a modified version of the diagram has recently been published [1], and further modifications are in process [private communication]. Here is the figure’s original caption: A framework for modeling in a physics laboratory involving (A) construction of a model of a real-world physical process, (B) making predictions about the behavior of the physical system, (C) creating a model of measurement tools, (D) using the measurement model to interpret the data and understand the limitations of measurements, (E) make comparisons between the data and predictions, and (F) model refinement.

Figure 3

An iron disk is tossed onto a cart where it bounces and slides. For the model-breaking assessment (Appendix pp2), students were asked if the total momentum of the disk and cart before the collision was the same as their combined momentum after the collision despite the obvious messiness of the collision itself [43].