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




Are we sure that there is NO educational value in "verifying" labs?
That's a strong claim, and if it is true, I am troubled to hear it because
I sure do a lot of them in my first-year high school physics classes.

I said less value, or at least meant to say that. So here is some evidence.
You can judge on the face of the evidence as to how valuable verification
labs might be.

There is an experiment where students were asked to investigate how the
force on one object relates to the force on another object. As a control
the investigator had other classes verify NTN3 by trying to disprove it.
The result was that the inquiry class understood NTN3 better, and had fewer
doubts about it. This was reported in TPT probably 10 years ago. Both
groups learned, but the inquiry group had firmer learning. We do not know
if an equivalent paper and pencil task could work as well as the
verification lab because that experiment was not done.

While verification labs may work as well as inquiry labs for conventional
evaluations, the research shows that inquiry improves student thinking, but
conventional education does NOT. The front end of the learning cycle is
inquiry or what has been also called exploration. The learning cycle was
shown by Karplus, Lawson, Renner and others to improve student thinking
when all 3 parts were done in the correct order. Indeed Anton Lawson has
also shown that inquiry also produces an increase in IQ as measured by a
general IQ test, so the increase actually shows up on 2 measures.

Similarly Perry showed that giving students methods with or without meaning
killed transfer. Schwarz's PPT also shows the same thing, but he has
managed to put algorithms in, but after students struggled in groups without
knowing the answer. Notice that verification labs are giving the student
the algorithm on the front end. Both of the cites to these papers were
given in a previous post.

Similarly Shayer & Adey use inquiry labs to raise the scores on a Piagetian
test and on a delayed standardized test.

So my claim is that inquiry labs produce superior outcomes in general. But
they have to be guided inquiry as Sadler has shown that free inquiry helps
only the top students and hurts the lower ones.

The evidence in favor of inquiry labs is quite strong.

If you consider the evidence from Mazur & Crouch that standard
demonstrations have basically NO effect on student understanding, it is
entirely possible that verification labs are similarly weak. But I have no
research to cite that shows this. I seem to recall there have been some
experiments which show that verification labs are very weak in promoting
understanding, but I can't put my dyslexic memory on it. Crouch may have
done some work on this.

All labs certainly can improve the ability of students to work with
equipment, just as drill in arithmetic improves memorization of math facts.
After all it is a form of practice, and I already pointed this out as being
a value. But I seriously question their value in promoting understanding.
Some of these labs can even be fun and possibly motivating for students.

One way of testing to see if they are working is to use a standard
psychological measure of engagement. I have not used them, but they are
available and are used by cognitive scientists. The only problem with
measuring engagement is that it does not measure what students are actually
learning.

Notice that I have a number of arguments based on firm evidence in favor of
inquiry labs, but I have not seen any good evidence in favor of verification
labs. If I can have some good research papers that show beneficial effects
from verification labs, I would be glad to consider them and possibly change
or soften my paradigm. But NOBODY has come up with any, so as far as I can
tell the evidence in favor of verification labs is zero. Also ALL of the
PER labs and materials that I am familiar with avoid verification labs.

After all we claim to be scientists, so can anyone come up with some
evidence?

Scientists are not exempt from the usual human way of thinking. We see bits
and pieces of evidence in isolation and then seek to understand the pattern.
But we forget or discard the pieces that do not agree with our paradigms.
This is how fortune tellers manage to stay in business. The clients forget
the wrong things and interpret many of the vague pronouncements to be true.
So when students say "I got it" we tend to remember it because it confirms
what we already know. We are wired to try to find patterns. Superstitions,
phobias, and science all come from that brain wiring. But in science we
have developed methods to sift out the random events and find mathematically
firm correlations.

All scientists operate with paradigms which they consider to be inviolable.
So does this mean we have "true religion" or "faith"? Perhaps. Remember
Einstein had faith that "God does not play dice with the universe". Nobody
would call that "true religion", so why question someone else's convictions
which have been carefully built up on evidence by calling it religion? I do
change some of my opinions when I see evidence!!! Incidentally Einstein
used God as a metaphor. One time when invited to go to services he declined
and said that he had been away from them so long that he feared that God
would not recognize him.

John M. Clement
Houston, TX