Comparing three methods for teaching Newton’s third law
Summarized by Jhonatan Esteban Lopez Bocanegra
I. INTRODUCTION
This study compares the effectiveness of three different tutorials (TIP, ABT, OST) in teaching Newton’s third law to students in the General Physics I course at the University of Maine. The aim is to observe differences in student learning by randomly assigning a tutorial to a section.
II. INSTRUCTIONAL MATERIALS
The study examines Newton’s third law in pushing and collision situations using three guided-inquiry tutorials. The Tutorials in Introductory Physics (TIP) tutorial, used as a control group, emphasizes confronting and resolving incorrect answers. It includes situations of unequal mass objects being pushed by an external force.
The Activity-Based Tutorials (ABT) tutorial uses microcomputer-based laboratory data acquisition techniques and low-friction carts and force probes to allow students to perform qualitative experiments involving both pushing and collision situations. The Open Source Tutorials (OST) tutorial emphasizes the refinement of students’ intuitions when studying Newton’s third law, taking students through a series of observations and thought exercises designed to refine their raw intuitions.
All three tutorials were written for different populations and do not require any advanced mathematics to complete. They all assume knowledge of Newton’s second law and kinematics, and that Newton’s third law has been discussed in class prior to tutorial instruction. However, the OST tutorial can function independently of this constraint.
III. RESEARCH STUDY DESIGN
The study design involved dividing the tutorial portion of the PHY 111 course into six sections, with each type of tutorial administered to two sections. Data was gathered from post-lecture, pre-tutorial pretests, post-tutorial homework, course examinations, and the Force and Motion Conceptual Evaluation (FMCE).
The data analysis involved examining preliminary pretest data to categorize the errors students were making in their thinking about Newton’s third law. Most student responses could be classified into three categories: action dependence, velocity dependence, and mass dependence responses. The study also used facets of reasoning to describe student responses.
The study identified three major facets of reasoning used by students when thinking about Newton’s third law: action dependence, velocity dependence, and mass dependence. These facets were used to analyze and code the pretests to quantify facet use. Each student was given a score representing the number of facets used for each type of situation (pushing or collision), with a maximum score of three facets per situation type, or six facets total. Over 90% of the students in the class used at least one incorrect facet on the pretest.
Students in the Open Source Tutorials (OST) performed significantly better on collision questions compared to those in the Tutorials in Introductory Physics (TIP) and Activity-Based Tutorials (ABT). Despite focusing on pushing situations, TIP students also improved on collision questions. However, all tutorials showed only small improvement in pushing situations.
VI. CONCLUSIONS
The study concludes that the “refining raw intuitions” tutorial is more effective than either the Tutorials in Introductory Physics (TIP) tutorial or the Activity-Based Tutorials (ABT) tutorial at improving students’ understanding of Newton’s third law. This conclusion is consistent across multiple measures, including pre-instruction quizzes, post-instruction graded assessments, and the Force and Motion Conceptual Evaluation (FMCE).
Improvement was primarily seen in understanding of collisions rather than objects pushing one another. All groups improved on examination data, but students in the Open Source Tutorials (OST) showed the most improvement. The study suggests that curriculum developers should focus on both pushing and collision situations to help students develop a more complete view of Newton’s third law.
