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Adepted by DW1 BarometerBarometer Or, THERE ARE MANY CORRECT WAYS TO ANSWER A TEST QUESTION.

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Presentation on theme: "Adepted by DW1 BarometerBarometer Or, THERE ARE MANY CORRECT WAYS TO ANSWER A TEST QUESTION."— Presentation transcript:

1 Adepted by DW1 BarometerBarometer Or, THERE ARE MANY CORRECT WAYS TO ANSWER A TEST QUESTION

2 Adepted by DW2 Story background: A physics teacher was about to give a student a ‘ zero ’ for his answer to a test question. The student claimed that he would receive a 100, if ‘ the system ’ were not so biased against him. Teacher and student agreed to submit the issue to a mediator.

3 Adepted by DW3 The test question was: “ How to determine the height of a very high tower with the aid of a barometer? "

4 Adepted by DW4 An idea ?

5 Adepted by DW5 The student's answer was: Take the barometer to the top of the tower, attach a long rope to it, and lower the barometer to the ground. Pull it up, measure L rope and L barometer. L tower = L rope + L barometer

6 Adepted by DW6 The mediator ruled that: The student really had a case for full credit since he had answered the problem completely and correctly. Yet, full credit should certify that the student learned his physics, as confirmed by the answer.

7 Adepted by DW7 Mediator ’ s resolution: The student will have another try at answering the question. This time the answer should indicate some knowledge of physics. After some minutes, the student said that he had several answers and he was thinking which would be the best.

8 Adepted by DW8 Any idea ?

9 Adepted by DW9 Then, the student went: Take the barometer to the top of the tower. Lean over the edge of the roof, drop the barometer, time its fall with a stopwatch. Use H= 1/2 g t^2 to calculate H. The teacher agreed to give the student nearly full credit.

10 Adepted by DW10 Any idea ?

11 Adepted by DW11 As the student had other answers, we asked him what are they: Take the barometer out on a sunny day and measure the height of the barometer, the length of its shadow, and length of the tower's shadow, then use simple proportion to determine the height of the tower.

12 Adepted by DW12 and more … Take the barometer and begin to walk up the stairs. As you climb, you mark off lengths of the barometer along the wall. You then count the number of marks to get the height of the tower in barometer units.

13 Adepted by DW13 and more … Tie the barometer to the end of a string, swing it as a pendulum, and determine the value of 'g.' The height of the tower can, in principle, be calculated from this.

14 Adepted by DW14 and more … And ….. without the limit of physics, you can take the barometer to the engineering department of city hall. There, tell the engineer, that you have a fine barometer, and he ’ ll get it as a present, for telling you the height of the tower.

15 Adepted by DW15 Finally, the student admitted that he even knew the textbook answer: Measure the air pressure at the bottom and top of the tower Apply the formula illustrating that pressure goes down as height goes up. … but he was so fed up with teachers who expect only formal answers, that he decided to rebel.

16 Adepted by DW16 Summary The teacher seriously considered changing the student ’ s grade to full credit. The End


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