Aps-ajp-11-1001-Book indb
B. Mismatch for 9-12 teachers: Example from kinematics
Download 231.88 Kb. Pdf ko'rish
|
6404f97bd5c2c-teacher-education-in-physics
- Bu sahifa navigatsiya:
- C. Mismatch for K-12 teachers: Example from electric circuits
B. Mismatch for 9-12 teachers: Example from kinematics
Concepts from kinematics are taught in several K-12 grades, beginning in elementary school. Students encounter the concept of acceleration in high school physics and some- times in middle school physical science courses, often in connection with objects that are falling freely or rolling down an incline. 763 763 Am. J. Phys. 74 共9兲, September 2006 http://aapt.org/ajp © 2006 American Association of Physics Teachers Teacher Education in Physics 147 148 Teacher Education in Physics In an investigation that extended over several years and included several colleges and universities, we examined stu- dent understanding of kinematical concepts in one and two dimensions. 5 In one problem used in this study, students were shown a strobe diagram of a ball rolling up and down an inclined ramp and were asked to draw acceleration vec- tors at various points along the trajectory 共see Fig. 2兲. We examined the responses from about 15,000 students in intro- ductory physics, 180 preservice and inservice teachers 共pri- marily grades 9-12 兲, and 300 physics graduate students who were teaching assistants in the introductory course. The most common incorrect answers were that the acceleration would be zero at the turnaround point, or that it would be directed vertically downward at all points. Only about 50% of the teachers and 20% of the introductory students drew correct sketches with acceleration vectors of constant magnitude al- ways directed down the ramp. About 75% of the graduate students gave correct responses. C. Mismatch for K-12 teachers: Example from electric circuits The topic of electric circuits is part of many precollege curricula, often in the context of batteries and bulbs. In our research on student understanding of this material, we have administered a wide variety of questions. One, which is based on Fig. 3, has been given to several different popula- tions, including introductory physics students and preservice and inservice teachers of all grade levels. 6 The question asks for a ranking of the brightness of the identical bulbs in the three circuits, which have identical, ideal batteries. Explana- tions are required. The correct ranking is A = D = E ⬎B=C. The results from introductory students and K-12 teachers have been approximately the same. Only about 15% in each group have given a correct ranking. The preservice and in- service teachers performed similarly, even though many of the latter had previously taught this topic. Analysis of the explanations by all the populations, including high school physics teachers, revealed the widespread presence of two apparent beliefs: the battery is a constant current source and current is “used up” in a circuit. The results from this question and from the one on balanc- ing discussed earlier illustrate a general finding. Teaching a topic does not necessarily deepen one’s own conceptual un- derstanding. The following event, which occurred during a professional development workshop, is illustrative. A high school teacher with 12 years of classroom experience had just completed experiments and exercises intended to help students associate bulb brightness with current. When asked to compare the brightness of a single bulb across a battery with that of two bulbs in parallel across a second battery, she observed that all three were equally bright. Surprised, she exclaimed, “That would mean that the amount of current from the battery is different in different cases, and that doesn’t make any sense!” She suddenly realized that her as- sumption that the current through a battery is always the same was incorrect. Although she was likely adept at solving textbook circuit problems, her understanding of the material was far short of what it should have been. Download 231.88 Kb. Do'stlaringiz bilan baham: |
Ma'lumotlar bazasi mualliflik huquqi bilan himoyalangan ©fayllar.org 2024
ma'muriyatiga murojaat qiling
ma'muriyatiga murojaat qiling