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6404f97bd5c2c-teacher-education-in-physics
Assessment of student learning. We have assessed student
learning by comparing results from pretests and post-tests. The following post-test question, which requires multistep reasoning, is an example. A system of three incompressible blocks is pushed across a frictionless table by a hand that exerts a constant horizontal force 共see Fig. 4兲. 16 Students are asked how, if at all, the acceleration of block A and the net force on block A changes if block B is replaced by a block of greater mass while the hand continues to exert the same constant force. To answer correctly, students must recognize that the inertial mass of the system has increased while the net force on the system 共due to the hand兲 remains unchanged. Newton’s second law may be applied to determine that the acceleration of the en- tire system and thus that of block A has decreased. Using similar reasoning, the students can then infer that the net force on block A has also decreased. When this question was administered in introductory physics courses after standard instruction, fewer than 20% of the students 共N⬎100兲 answered correctly. 7 About 90% of the teachers 共N=45兲 who worked through the Dynamics module gave a correct response. We have also given this question to introductory students after they had worked through Tutorials in Introductory Physics. 17 共This curriculum addresses the intellectual issues discussed previously, but in a form adapted to a large introductory course. 兲 About 55% of the students 共N⬃720兲 answered correctly. Although this re- sult represents a sizable gain over that obtained with standard instruction, it is not good enough for prospective teachers. Even when an introductory physics course is supplemented with research-based materials, students are unlikely to de- velop the depth of understanding that is possible with the type of instruction provided by PbI. There is evidence from other topics that not only is the resultant gain in conceptual understanding greater, it is also persistent. 18 Commentary. To illustrate our instructional approach in preparing teachers, we have used an example from dynamics. A topic from earlier grades would have served equally well. Elementary and middle school teachers need the same type Fig. 4. Question about Newton’s second law. 共a兲 Students are shown a figure in which three incompressible blocks are pushed across a frictionless table by a hand. 共b兲 They are then told that block B is replaced by a block of greater mass. The question asks how, if at all, the acceleration of block A and the net force on block A change if the hand exerts the same horizontal force in both cases. 765 765 Am. J. Phys., Vol. 74, No. 9, September 2006 McDermott et al. 150 Teacher Education in Physics of preparation. Although the topics that they are expected to teach may appear simple to a physicist, it takes a significant amount of time and effort to develop the depth of under- standing needed to teach this material in a coherent manner, rather than as a set of separate activities. Download 231.88 Kb. Do'stlaringiz bilan baham: |
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