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STC PROGRAM
Update
Winter 2003
Most teachers agree that having live organisms in
the science classroom for students to observe and study adds much to the
learning experience. Several STC® units and one STC/MS™ module include live
materials, and care and handling instructions are provided (either in an
appendix in the STC Teacher’s Guide, or as a separate instruction sheet for
the STC/MS module). No, you don’t have to brush your fiddler crab’s teeth,
but you do need to follow closely the care instructions. Occasionally,
however, differences in your local water, local climate, classroom
environment, and other factors can make caring for the organisms more
challenging than expected.
Here are some additional tips we’d like to pass along that can help you
maintain healthy organisms while working with an STC® or STC/MS™ kit.
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For aquatic organisms,
care instructions included in the Teacher’s Guide or shipped with the
organism specify dechlorinated tap water for use in the holding pails
and habitats. Typically this works fine, but we’ve heard from a few
teachers whose critters arrived in good shape but then died unexpectedly
soon afterward.
The water in the holding pails or habitats may be a factor. Carolina’s
Living Zoology staff suggest that even when you dechlorinate local tap
water (using the conditioner included in the STC® kit), the water’s pH
still may not be in the proper range for the animals’ survival.
In
addition, local water can contain minerals in a higher concentration
than small aquatic animals can tolerate. When organisms are very
small, even trace amounts of a foreign substance can be lethal. If you
follow the recommended care instructions and still have problems with
organisms dying, the next time you teach the unit consider using bottled
spring water (NOT distilled water), available at most grocery and large
discount retailers, rather than tap water. Spring water does not need to
be dechlorinated. |
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Remember that plastic
tanks, holding pails, dip nets, and other equipment used with living
materials should not be washed with any kind of soap. Even if the items
are thoroughly rinsed, trace amounts of soap residue left behind can
kill the organisms. If you need to clean any equipment that has been
used with your living materials or their habitats, use a clean cotton
cloth or sponge, moistened with water only, to wipe off scum build-up.
(If the residue is difficult to remove, try using a soft-bristled brush
or a no-scratch scour pad, such as those recommended for cleaning
nonstick cookware.) Then rinse the object thoroughly in clean water. |
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If conserving energy is a
major emphasis in your school or district, maintaining an adequate room
temperature for your living organisms during winter months will be a
particular challenge that should be considered before the organisms
arrive. For an STC teacher in the San Francisco area, teaching the
Ecosystems unit one spring did not go as planned. To deal with a rapid
and significant increase in the school’s heating costs, her school
turned the heat down to 50° F at night. Unfortunately, guppies—which
need their water kept in the 68 to 78° F range—don’t have coats to put
on when the water temperature goes down in an unheated ecocolumn. So
when a cold spell sent the Bay area’s evening temperatures plummeting
into the 40s, the guppies didn’t fare well.
Moral of the story: If your
school or district requires lights and/or heat to be turned off or cut
back when school is not in session (at night or on weekends), living
organisms such as Wisconsin Fast Plants™ or guppies will not thrive as
they should, and during winter months they may even die.
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