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Asia-Pacific Forum
on Science Learning and Teaching, Volume 10, Issue 2, Article 3 (Dec., 2009) |
In the interviews, students were expected to use the linear momentum principle, the energy principle, and the angular momentum principle even though students were not instructed to use these principles just before the physics problem-solving protocol. At the beginning of the study, most of the students were not using expert way of solving problems especially we were looking for whether they were using the fundamental physics principles such as the linear momentum principle to solve the problems instead of starting with equations.
Some students did not use the momentum principle in the first interview. They preferred to use the Newton’s third law instead. The reason can be that students learned to solve this kind of problems using Newton’s 3rd law in high school. On the other hand, after I asked them to use it they were able to use it. Before the interview, I did not ask or instruct them to use it since the course is based on using these principles. On the other hand, this does not show they were not able to solve the problem. They used an alternative approach, which is the Newton’s 3rd law, to solve it. In general, students may use particular aspect knowledge to answer a question or solve a problem. The following sections explain how students’ performance altered throughout the course.
The First Problem-Solving Protocol: Application of the linear momentum principle and obtaining Newton’s 3rd Law from the linear momentum principle
Only one student used the linear momentum principle to solve the problem and made the connection with Newton’s 3rd law. One student used Newton’s 3rd law and solved the question correctly. After the researcher asked him to use the linear momentum principle, he was able to use it and got the correct answer as well. Therefore, this indicates that students can use the linear momentum principle too. In other words, students who have sufficient understanding or experience acted like experts. Four students acted like experts and two students acted like novices. The other students solved the problem after some assistance. Unfortunately, three of them had conceptual difficulties and used only pieces of knowledge. Their content knowledge was fragmented. They have p-prims (diSessa, 1993). For example, their p-prim is “the bigger mass exerts the bigger force.” They also were not able to make connections between the linear momentum principle and Newton’s 3rd law. There might be a number of possibilities that account for some of the difficulties being observed in how students answered the question. These possibilities include the fact that the first interview was at the beginning of the semester, so students might not be familiar with the linear momentum. If they were, they would not have p-prims (diSessa, 1993) because they would get Newton’s 3rd law from the linear momentum principle and saw that it does not matter having different masses. Since they used directly F=ma, they thought that the bigger mass had the bigger force.
The Second Problem-Solving Protocol: Application of the Energy Principle
All students solved the problem correctly by using the energy principle except one. Three students especially really did a good job on this problem. They used the energy principle, made the approximations correctly, and solved the problem while explaining each step well. Also, Thomas did a very good job on the conceptual part of the problem; however, he made a calculation error. Later, he realized his mistake and corrected it. The one who was struggling was Jennifer. She knew that she needed to use the energy principle, but she did not know what kind of energies would be involved. After some assistance, she did correctly. Consequently, the results appeared that students seemed to improve their problem solving ability since the first interview. In the first interview, while only two students solved the problem without prompting, four students solved the problem without prompting in the second interview.
The Third Problem-Solving Protocol: Application of the Angular Momentum and Energy Principle
Jennifer did not join in this interview. So, there were five students. Two of them were good. They used the angular momentum and energy principle correctly and made correct approximations. They did not have any problem with finding the rotational inertia of a combined system, although Clark had a problem with it even though he used the angular momentum and energy principle. Elizabeth and Thomas had some conceptual difficulties. Elizabeth had pieces of knowledge, and she tried to use them. She used the angular momentum and energy principle after some assistance. Thomas had a mathematical problem too, because he had a problem with cross product. He did not have any problems using the angular momentum, but he did with the energy principle. He used the energy principle after some assistance. From the results of the third interview, even though it may not show that there is an improvement in students physics problem-solving ability, they were aware of using the angular momentum and energy principle. There might be some reasons for not showing improvement. One can be that the third interview was at the end of the semester and students did not care much about solving the problem. The second one can be that this topic in physics is a hard topic to grasp easily, so, they were struggling solving this problem, with the exception of John and Mark. The performances of John and Mark were really good from the first interview. So, it is difficult to tell whether their problem-solving ability improved. As for Jennifer, my guess from her previous performance is that she would have some difficulties too if she joined the third interview.
Does the modeling-based instruction and interactive engagement promote students’ problem solving ability and have students act like experts or not?
Protocol analysis of six students' problem solving process revealed that some students had the potential to improve their problem solving ability even though students’ performance on the third problem solving protocol was lower. Students analyzed problems qualitatively before they attempted quantitative manipulation or using equations to analyze problems. Students increased their reliance on the use of principles in writing qualitative explanations of physical situations. Students’ shift toward the expert-like competencies was observed. In other words, students had the potential to improve in their problem-solving performance. It was concluded that the modeling-based interactive engagement teaching approach demonstrated a success in improving students’ problem-solving ability under the constraints of the study such as last interview was conducted during finals week that could affect their performance on problem solving because their minds were occupied by their exams. The research can provide evidence in favor of this instruction in terms of its success in using qualitative analyzing of the physics problems by using the fundamental physics principles.
The implications of this research in terms of instructional strategies to promote physics problem-solving ability:
The research has shown that the modeling-based interactive-engagement teaching approach can promote students’ problem solving ability, so this approach can be used to teach an introductory physics course. The approach using a modeling-based interactive engagement can facilitate opportunities for students to make their problem solving processes explicit to promote their problem solving ability. In other words, students’ thinking can change towards expert thinking and positive attitudes even if they cannot completely value the 3rd problem.
Acknowledgements
I would like to thank to Dr. Donna Enersen for her noteworthy help. Also, I am thankful to the head of the physics department, Prof. Andrew Hirsh, and PHYS 162 and 163 students at a major state university in the US. Also, I would like to thank Prof. Vanitha Saravanan for her editorial constructive comments and suggestions on revision of this manuscript.
