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Re: [Phys-l] unbiased experiments +- index of refraction




Maybe I'm just old and thickheaded, but 90% of what you have described is
simply what is usually tagged as a "meaningful lab experience". Your claim
is that that research has shown that these "discovery" or "inquiry"
approaches are superior to traditional lab exercises, but you examples are
what I feel are simply part of the spectrum of labs that are well thought
out with specific goals in mind. I'm not sure what they are actually being
compared to as a control. I really don't think there are many experienced
faculty out there that simply have students robotically go through cook
book procedures and call it a lab.

I guess I really don't have a grasp of what makes these "discovery" labs
different enough to warrant a new name and an enthusiastic set of
disciples. I certainly see that the motivation behind this approach is
different enough to assign a new name, but the nitty gritty details of
what happens in the labs sounds too familiar and close to what reasonable
people already do.


If you see them as being meaningful then there is not problem with doing
this type of lab. The main difference between inquiry and verification is
that in verification the students are told what equations they will use and
essentially what to expect. In inquiry the process is in the reverse. They
are never given the theory before the experiment. The experiment is the
front end for the theory or the model. Then the experiment can be used as
the paradigm for the theory.

When students do the walking lab with the motion detector they have already
had the definition of velocity from a previous lab where it is defined as
the slope of the position time graph. They see a graph of velocity-t on the
screen that they must match. If it shows the velocity rising almost
instantaneously then flattening out they have difficulty reproducing it.
They first try jumping and then standing still. I always ask things like,
describe the graph. What is happening to the velocity in the flat part?
How do you achieve constant velocity? Eventually they figure it out.

To learn reasoning they have to do it. They have to be prompted to make
connections, without being told the connections.

Workshop physics uses a double ended spring scale that you can purchase
commercially. When students started using it to just measure various pairs
of interaction forces, their understanding of NTN3 went to 90% or better.
Inquiry labs have lower engagement because students already supposedly know
the answer. I can remember doing an NTN3 lab with 2 spring scales, but had
already been told about it. I thought it was stupid at the time.

Now you may already be doing the sorts of things that work well, but you
can't tell unless you use some standard tests like the FCI or Lawson's test.
You may actually be doing inquiry labs most of the time! Actually gain the
Lawson test is much more valuable than on the FCI. With higher Lawson
scores students can do better in any field of science or math, but higher
FCI might not help them in biology. But Lawson score gain is much more
elusive.

John M. Clement
Houston, TX