From: Ben Pittenger (benpittenger@earthlink.net)
Date: Fri Jan 24 2003 - 08:31:17 PST
Message-ID: <5506790.1043425886542.JavaMail.nobody@gonzo.psp.pas.earthlink.net> Date: Fri, 24 Jan 2003 08:31:17 -0800 (GMT) From: Ben Pittenger <benpittenger@earthlink.net> Subject: raining pennies
As I reread this posting before sending it, it sort of
sounds preachy or nuts, or both. Please don't take it
that way. I'm just jotting down some ideas that went
through my mind.
I looked back at the original message on this topic
and noticed that part of the concern was the student
who hadn't shown much prior academic interest. So
how does he get pulled in? There are a couple of
things that come to mind. I wondered what sort of
thing I would have liked when I sat bored in classes.
I also know that I often hold my students' interest
better (and keep them participating) when I am leading up
to some exciting event over several days.
I would have the students estimate (hypothesize?) how
fast the penny would take to travel the length of a
football field. You could tell them that once they
each had a reasonable estimate you would take the
class out to the football to visualize their estimates.
Then take them to the field with a stopwatch. The
estimates of terminal velocity from our listserv
compatriots came out to about 85 - 93 m/s. So have
them look at two objects about 90 meters apart (happens
to be about 98 yards, so a football field about does it).
Then get them to move their vision over the length of
the field in one second, while thinking about a flying
penny, to visualize an object moving that distance
in one second.
Another question is how the penny would fall; would it
fall on edge, flat, somewhere in between, or would it
tumble? Here, it sounds like we're all guessing! So have
them build a hypothesis, then you could run some trials -
I know it would be a rough model, but maybe you could use
a local roof or second/third story window and drop a bunch
of pennies into a soft medium of some sort, and see how
they land - flat, on edge, at an angle, or in a variety
of ways. (We use our gym roof for our egg drop. It's over
10 meters; though students don't go up there!) High windows
would be better so the students could test their own methods
for dropping the pennies. For encouragement, let the
students know they will be reporting back their original
research to all these science teachers on the web!
Next would be the 'real' modeling. If I took this on,
I would try to use a pan of jello or maybe that
water-absorbent polymer they use on plants. (I bet the
students would each bring in a couple of boxes of gelatin
if they knew what it would be for!) I would spread it in
a large pan (for a large target), with some sort of surface
to model skin, like a layer of thin leather, plastic wrap,
or cellophane. Again, have them hypothesize what the
result would be - and have them justify their hypotheses
with some sort of research or information.
It might be worth approximating the same momentum of the
penny by using a more massive object from a lower height.
The students could debate the validity of this model
(larger - so different shape/size; but better estimation of
momentum). The object could be dropped from an accessible
rooftop or stepladder.
A month or two ago you could have used leftover pumpkins to
model a skull. (Didn't one of our esteemed leaders in
washington use a pumpkin a few years ago in an attempt
to model a gunshot suicide?) I did drop a couple of
pumpkins from the gym roof during our egg-drop a couple of
years ago after discussing stess, strain, and catastrophic
failure of pumpkins during a Halloween exercise.
I sure would be curious to hear what your students'
results would be!
Ben Pittenger
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