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[Physltest] [Phys-L] Re: California standards test in physics



On 1/5/05, I wrote:
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What do you folks think of the following questions:

3. A student wires a series circuit that includes a
block of rubber and a light bulb. She states that
she does not expect the light bulb to light up
when current is applied to the circuit. Which of
the following best describes her statement?
A It is a conclusion based on observed data
about electrical phenomena.
B It is a hypothesis based on knowledge of the
theory of electrical phenomena.
C It is a procedure based on her hypothesis
about electrical phenomena.
D It is a theory based on her observations of
electrical phenomena.

8. A ball is thrown straight up and then falls
straight back down. When it attains maximum
height, the ball's velocity is
A equal to its displacement.
B equal to its displacement divided by the time.
C at its maximum.
D at its minimum.
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Thanks to all of you who responded to my original question that started this
strand. Now I'd like to let you know what I think of these questions. Not
much obviously. Many of my opinions have already been mentioned by others.

Problem 3.
i. Current is not applied to a circuit. Current is usually said to be
injected into a circuit.
ii. The logical way to read this question is as follows: Suppose a certain
amount of current is applied to a circuit containing a light bulb and it
lights up. Now suppose that I inject the same amount of current into this
circuit, which now includes a block of rubber. As I see it, there is no
other logical way to interpret this problem. In this interpretation, the
light bulb will of course light up. So the question is immediately
confusing. And it indicates that the test writer does not really understand
the difference between current and voltage.
iii. The answers.
If the student had made this circuit at an earlier time, one could conclude
that her statement is based on her observed data. So A is correct.
If the student knew about the electrical properties of materials and
circuits, but had not done the experiment yet, she could hypothesize that
the circuit would not light. So B is correct.
If the student knew about the electrical properties of materials and
circuits from previous experiments, she could make a theoretical prediction
about the behavior of this circuit. So D is correct.
One has to also ask the question: what is the point of this question? Does
this question demonstrate the student has some understanding of how science
is done? I think not.

Problem 8.
i. As others have pointed out, the question is really asking about the
ball's speed. Since this is a high school level question that mentions
velocity, one would assume that students (and the test writer) know the
difference between velocity and speed. Apparently not.
ii. If the ball is thrown up with a velocity of 2 m/s, at the top its
velocity is 0 m/s and it lands with a velocity of -2 m/s, then obviously the
ball has neither its maximum or minimum velocity at the top. This assumes
that the students (and the test writer) know about negative numbers.
Therefore, the correct answer is not shown.

I'd give both questions a failing grade.

Larry Woolf
General Atomics
San Diego, CA 92121
<http://www.sci-ed-ga.org>
<http://www.ga.com>
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