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Article Excerpt
With computer-based instruction, numerical data collection and analysis are performed effortlessly in the laboratory, simulations with idealized conditions are a click away, and abstract concepts that are difficult to visualize are represented in full-color animated displays. Many of these computer applications are designed to help students understand physics by clearly presenting the outcomes of physics or by making it easier to do scientific experiments. However, in the effort to get to the product of science, is there a danger of misrepresenting the process of science? This is a particularly important question in college science classes for future teachers where we try to model instructional practices that promote inquiry and active learning. If we want students to take responsibility for building their own understanding of science, they need to develop an understanding of what science is. In this study, we look at pre-service teacher classes in physics, one of which uses computer-based laboratories extensively. The context presented is one-dimensional motion, which is covered in the computer-based class with motion sensors interfaced to computers. We consider student performance in an interview setting and on an examination problem.
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In the implementation of teacher education programs, there is a call for teachers to learn "science content through the perspectives and methods of inquiry" and to use "technological resources that expand their science knowledge" (National Research Council, 1999). With computers, science teachers have opportunities to engage students intellectually, to explore more meaningful and exciting subject matter, and to learn the technology itself.
In this paper, we use student interviews to probe learning in a physics class for future teachers. The class used motion sensors as a focal point of instruction. We find that after instruction, some students do not connect their qualitative understanding of the material to the formalisms developed in class. One stated "I'm sticking with my formulas instead of my thoughts" when trying to resolve an apparent discrepancy. Other students are unable to interpret experimental data obtained with non-computer based equipment. For example, one completely changed her analysis of an experiment to account for typical measurement errors. We also look at how students in different classes (using different methods of instruction to cover the same material) performed on the same examination problem. The relationship between computer-based instruction and student performance is explored and implications for instruction are discussed.
STUDENT INTERVIEWS
Classroom Context
Student interviews were conducted with pre-service teachers enrolled in a popular computer-based introductory physics class for future teachers. The class, Phys 115 at the University of Maryland, is intended for students interested in teaching in elementary or middle school. The goals of Phys 115 go beyond teaching subject matter. They also include helping future teachers realize that science is accessible, exciting, and relevant to students of all ages and that science involves doing and understanding, not just memorizing.
Phys 115 is extremely hands-on and interactive. In the particular class studied, most of the experiments conducted were microcomputer-based laboratories (MBL). For many years MBL have been successfully implemented in college physics courses (e.g., Thornton & Sokoloff, 1990; Laws, 1991). For about five weeks in Phys 115, there was an emphasis on using motion sensors combined with graphs in teaching about motion. Before using the computers or doing the experiments, students made predictions about what they thought the graphs would look like as they moved in different ways in front of the sensors. After carrying out the experiments, they compared the results with their predictions and accounted for any differences. They considered multiple representations of motion including graphs and equations. In addition, students were constantly articulating their understanding in words and explaining their reasoning.
Investigations of student learning in college physics courses suggest that these kinds of strategies and tools are better than traditional instruction at helping students understand physics concepts (Redish, Saul, & Steinberg, 1997; Steinberg & Oberem, 2000). Furthermore, students in Phys 115 showed strong gains with respect to attitude and affect. There is no question that the students began to appreciate the value of an interactive and collaborative science classroom. Student comments about learning science while taking Phys 115 consistently reflected significant gains in perspective on the teaching and learning of science. For example, one student noted "When I have learned science in the past it has been purely memorization for a test and then I forget it. [Phys 115] is very hands on though, so I can actually see what I am doing and understand what I am learning." Another said "I've learned that interesting relevant topics and hands on learning experiences that demand thought and each person's ideas are the most effective way to teach people science." However, the purpose of this research was to study Phys 115 students' understanding of the nature of science having learned extensively in an MBL environment.
Protocol
During the last week of the term, eight students out of the 27 enrolled in a Phys 115 class were interviewed. All were undergraduates. Seven were elementary education majors. The eighth was planning to become one. The students volunteered to participate in the interviews and tended to be doing well in the course. Five of the students received an A, two a B, and one a C. The students were interviewed one at a time and each interview lasted between 45 minutes and an hour. The interviews were videotaped and transcribed.
To various extents, the students demonstrated conceptual difficulties similar to what has long been observed in traditional physics classes (Trowbridge & McDermott, 1980; Trowbridge & McDermott, 1981). Some could not distinguish velocity from acceleration. One said, "you would have to measure the velocity, which is the acceleration or the speed." Another said, "acceleration is the speed of it and velocity, I don't know, it's just another word." Other students used meters and inches interchangeably or used flawed measurement technique. In this paper though, the focus is on difficulties students had carrying out and interpreting scientific experiments involving motion.
The interview protocol consisted of two distinct tasks. The subject matter on which they were based was covered in the course. For the first task, students were shown a strip of paper containing a series of dots with times written next to them. (See Fig. 1.) The interviewer explained that the dots were created by a cart rolling in a straight line and marking the trail at the clock times indicated. After being sure that the students understood how...
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