scientific method labs

Anne Heise aheise at ORCHARD.WASHTENAW.CC.MI.US
Thu Aug 7 08:37:19 EST 1997


The first lab for the soph. level general botany course I teach is often
on the first day of class, so I like having a lab that students don't need
to have prepared much for.  For the past sev. years it's been a scientific
method lab.  The one I've tried a few times is to have students put a leaf
in some boiling water, hopefully observe the bubbles escaping from the
leaf, and ask them to test as many hypotheses as they can about that
observation (e.g. it's the water, not the heat of the water, that causes
the bubbles to escape).  But this hasn't been as reliable as I've hoped.  

A few days ago I thought of asking students instead to investigate the
browning that occurs when you cut open an apple.  Is it exposure to air,
is it the damage due to cutting, what about lemon juice prevents it from
occuring (e.g., is it the wetness of the lemon juice, its pH, or what?)
etc.
Not having tried this w/ students, I naturally think this problem could
work really well! It doesn't require much knowledge of plants, it should
be a familiar phenomenon to most, it won't cost a lot, etc.  I'm tossing
this little embryonic idea out to the group to see what other ideas people
have about scientific method labs, and whether you have any particular
comments about messing around w/ apples.

At the end of such a lab I have students do a very quick "poster session".
I supply overheads and markers s  and have  them  present one of their
experiments to the rest of the class.  They don't love this, but I think
it helps make the lab seem a little more important.

Another thing we do, I guess in the second lab, is critique a lab write-up
done by a student a few years ago.  This write-up has some good things and
some that aren't terrific, and my hope is that if students take the time
to figure out for themselves what is good and bad about someone else'e
write-up, they'll start producing good ones of their own a little sooner.
What else do you all do to help students write up labs well?

Anne Heise
Washtenaw Community College
Ann Arbor MI





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