Wes Davis said that college physics professors don't know much about the
limitations of HS students. That was true for me when I first started
teaching. But I just finished my 28th year, and not too much surprises
me anymore. It is interesting that when I was more naive about what
students didn't know, I was also more demanding. I had expectations
pretty far above their abilities. In addition, students at that time
(late 1970s) were a little more likely to blame themselves for their
inadequacies and a little less likely to blame me for being too hard.
Thus, many students rose to the occasion and came pretty close to my
expectations. Over the years as my understanding of "where students
are" has improved I have lowered my expectations, and students are less
likely to meet even those. I often wonder if I was a better teacher
when I was more demanding, and I wonder if I really would flunk most of
the class if I returned to that level, or if they would rise to the
challenge.
Jack Uretsky is stopped in his tracks when someone says "I tell
students..." Well be prepared for lots of stops... I tell students to
memorize the power-of-ten prefixes, and I tell students it will be on
the test (and it is on the first test as well as the second test), and I
tell students I will also be using these in the assigned problems (and I
do), and I tell students they will have to use them in their labs and
lab reports (and they do have to use them). I don't see any problem
telling (informing? warning?) students what is going to be required for
A-level work in the course and then following through with the
requirement.
So what's the problem? Various responders have hit upon some of the
problems. I want to mention a few I see that have not been mentioned by
others then make a few more responses.
(1) Students don't generally have to work with many conversions or
powers of ten in any classes other than physics. Over half of my class
is composed of biology, chemistry, pre-med majors. The chemistry course
they take concurrently with physics is organic chemistry. It is mostly
descriptive; almost nothing quantitative except some balancing of
equations and figuring percent-yield from a lab prep. The chemistry
they took last year was general-inorganic. That's mostly descriptive
and the lab has a lot of qualitative analysis in it. The quantitative
part is pretty tame; not much more than molarity, titrations and things
like that. There is a section on pH and on equilibrium chemistry, and
that is when my colleague (the professor for that class) pulls his hair
out.
The biology students have taken botany and are taking anatomy and
physiology. Zero math in those classes.
The computer science students have taken programming, data structures,
and are taking more data structures and object-oriented programming. No
need for unit conversions or powers of ten in any of those courses.
The pre-service science teachers ought to have interest because they're
supposed to teach this stuff some day, but they are high on superficial
interest and low on detailed interest. And unfortunately, many are
wanna-be coaches more than wanna-be science teachers. I still haven't
recovered from a discussion I had a couple years ago with a past physics
graduate. He majored in physics, reluctantly became a HS physics
teacher, and also the football coach. After a couple years he said he
had found his calling. He said he never knew teaching could be so fun
and rewarding. When I asked what parts of physics he found most fun and
most rewarding he said, "Oh, I didn't mean that. I meant coaching the
football team."
Bottom-line... I think most of my students figure my course is the first
course and the last course where they will have to struggle with such
ridiculous things as picofarads, microvolts, nanometers, kilojoules,
etc.
(2) Students have less appreciation of orders of magnitude now that they
are using calculators rather than slide rules or even pencil and paper.
We've already discussed in other threads about how students don't even
know how to enter numbers into their calculators. They are amazed when
I tell them (oops, just told them something again) that the EE key is
for entering the exponent. Of course I am amazed that TI calculators
tend to put the EE key as a 2nd function key. Right there is a strong
indicator that either (a) TI calculator designers don't know what
they're doing, or (b) their market research has indicated that most
people using their calculators don't use scientific notation very much
and so it makes sense to demote a rarely-used key to a 2nd-function key.
Again I am left to conclude that students just don't encounter a need
for large and small numbers outside of physics class, and when they do
encounter them they pick up their calculators and plug-n-chug and don't
think about the process or the result.
(3) John Clement said that students are often poor at proportional
reasoning. Yes, and I sometimes do exactly what John suggests. Suppose
a student asks for help with the capacitor lab and has inverted the
conversion from picofarads to farads.
ME: Is a picofarad larger or smaller than a farad.
Student: Smaller
ME: Okay, so if you are converting picofarads to to farads, do you
expect to get a really big number or a really small number.
Student: Big
ME: Is a penny larger or smaller than a dollar.
Student: Smaller. Are you telling me I did the picofarad thing
backwards?
ME: If you count the pennies in your penny jar and get
three-hundred-forty-two, is that a lot of dollars or not so many
dollars?
Student: I did the picofarad thing backwards didn't I. So if I switch
it around it will come out okay, right?
ME: I'm not going to tell you. You figure it out.
Student: Well if I didn't do it backwards you wouldn't be so stressed
out about it.
Goodness. Not only does he not understand how to think this through, he
doesn't even want to think it through. Apparently that's too painful.
(4) My HS and college experience was similar to Richard Tarara. But
students I see today are not stupid as Richard seems to think we were
saying. Ignorance, as suggested, is a better word. But there's more to
it than ignorance. "Lazy" is also a good descriptor. "Distracted" is
another.
What I mostly don't see is curiosity coupled with a desire to figure it
out. I am, always have been, a very curious person. (My wife will take
that wrong and will totally agree.) I don't see much of myself in most
of my students, and therefore I don't understand my students very well.
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu