Teaching Junior High School Physics: Personal Experiences and Observations
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Teaching Junior High School Physics: Personal Experiences and Observations In my thirty years as a university science and engineering professor, I have always wondered about the apparent lack, among American-educated students, of a basic understanding of fundamental physical principles. Why doesn't the average student know the functions of simple everyday devices such as a light bulb, an electro motor, a transformer, a battery, or a resistor? Moreover, why do these students apparently lack the joy and excitement of discovering the laws and secrets of nature? Part of the key to answering these questions undoubtedly must be sought at the lower educational levels. That is why I welcomed the opportunity to teach a "physics block" in a Waldorf school. In Waldorf schools, children are intensively exposed to a certain study area, such as chemistry, biology, history, or literature, for the first two hours of each school day, for three to four weeks. Waldorf schools also try, whenever possible, to combine various study areas. For example, teachers strive to intersperse physics with elements of philosophy, art, or history. My assignment was to introduce the 7th and 8th graders to the foundations of mechanics. Our first endeavor was to explore the laws of pulleys and tackles. To do this, we hung a pulley from the ceiling, threaded a rope around the roller, and attached bricks of equal size and weight to each end. Quite naturally, and to nobody's surprise, the bricks held each other in balance unless someone pushed or pulled on one of them. Next, we fastened one end of a rope to the ceiling and threaded the other end through a movable pulley on which we hung a brick. The free end of the rope was then strung around a fixed pulley which was attached to the ceiling. This end of the rope was connected to only half a brick. Then came the question to the class: Why is it that half a brick can counterbalance a full brick? The question was not immediately answered by the pupils. Several incorrect suggestions were proposed, including magic or tricks. We took our time. After half an hour of experimentation, guessing, and steadily increasing excitement, I asked one student to hold one of the bricks in each hand and to move the hands up and down. Suddenly she exclaimed, "I have to move one hand a much greater distance than the other hand!!" Now everyone wanted to try it. This took another 15 minutes or so. Finally, everyone seemed to have shared the revelation that a movable pulley halves the necessary force
while it doubles the travel distance. Philosophical remarks entailing how a weak person can double (or quadruple) his strength were discussed in order to bring this physical phenomenon into a larger, that is, human, context. At home, the pupils drew colorful pictures about the day's events in their own notebooks. On another day, when studying the laws of an inclined plane, we wondered how the ancient Egyptians might have brought their heavy stones to the top of a pyramid. We discussed that the Egyptians might have piled up a ramp, co
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