PP-AR Misconception Animation

Ross Koning koning at ECSUC.CTSTATEU.EDU
Wed Dec 8 12:00:57 EST 1999


Hi Linda!

To answer your question indirectly I would say that
animations are great and all that, but I'm a great
believer in the real world. There are some very
memorable exercises the students can do with real
live plants that demonstrate plants doing respiration
beautifully. To me, a misconception is best deposed
by real-world observations...the virtual world is
too easily contrived. Simulations are sometimes not
convincing to students; and for better or worse our
media convinces students that scientists are NOT to
be trusted.

One old standby is to put moistened germinating seeds
(peas, popcorn) in a test tube with cotton ball
over the seeds and a few pellets of NaOH or KOH.
The tube is stoppered with a one-hole stopper
fitted with a short length of capillary tubing
(or a very small ID pipette). A drop of your
favorite aqueous stain (methylene blue?) is put
on the end of the tubing/pipette. Respiration
removes O2 and the drop moves up the tubing. For
a control, boil half of the seeds and cool completely
to room temperature (overnight) and assemble in a
similar way. For discussion, repeat your project
leaving out the NaOH/KOH pellets in both tubes.

Another "live" project is to do the floating leaf-disc
assay for photosynthesis.  After a leaf-disc refloats
by putting oxygen gas in the intercellular spaces, it
can be put into darkness (put a film can over the
syringe body); the oxygen gas is used up by respiration
and the floating disc sinks.

You can get wonderful observations from the Qubit
system for a more advanced class.  This system is
great for a small class because it is much more
complex, expensive, and uses a computer interface.
The changes in oxygen content of a cuvette that
contains leaf tissue demonstrates both photosynthesis
and respiration depending on photon flux density and
so on. I just use leaves from the greenhouse or from
outdoors (don't need to be attached to a plant for
short-term tests). I reserve this system for my plant
physiology class. After they have tried some simple
manipulations "live", then I put them onto the Explorer
simulation. That simulation is excellent and quite
inexpensive (Prentice Hall approx $45)...I find using
my own customized exercises the best way to supplement
an actual cuvette project with this simulation. I can
build on what they learn first-hand.

ross

At 9:44 AM -0500 12/6/99, Linda Heath wrote:
>We've just been through the annual attempt to correct the "plants
>photosynthesize,
>animals respire" misconception in our non-biology majors labs.  Has anyone
>found animations that specifically deal with this or could be adapted to do
>so?
>
>I'm also interested in any approaches people use to help with this. When that
>"teachable moment" comes - what do you do/say and/or have the students do?
>
>How can we stamp out that cursed "PP,AR" phrase!!??!!  Hmmm, someone must be
>frustrated...
>
>Linda Heath
>Biology Department
>Xavier University
>Cincinnati, OH  45207-4331

________________________________________________________________
Ross Koning                 | koning at ecsu.ctstateu.edu
Biology Department          | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479
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