Ask A Scientist© Physics Archive

Question:  I am teaching a unit on electromagnetism to fifth graders.  I am also 
doing a maglev train experiment/race with them.  I need to find an elementary
way to explain electricity.  Can you recommend some books to show me the way
and what to explain?
ann
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Answer:  I would suggest using the CASTLE kits with your students.  These are
available through most scientific supply companies.  If that is too much
try getting a bunch of GENECON hand crank DC generators.  Have your students
crank the generators with progressively larger parallel and series circuits.
Use light bulbs as the loads.  With the parallel circuits the electrical
resistance obviously goes down with the addition of each new light bulb,
but it gets progressively harder to turn the crank at a constant speed
because of the increased demand for current (load).  The inverse effect
occurs with the series circuit as the electrical resistance gets larger
reducing the current and hence the load on the generator.  This is all
neatly explained with the standard fluid model of electricity.  I would
stay away from trying to explain this stuff with electric fields to fifth
graders.  The CASTLE kits use great big (one farad caps.  at 25 volts)
capacitors to further develop the fluid analogies in electricity and give
a sense of concretness, if you will, to something that is essentially
invisible.  The CASTLE kits come with excellent manuals with worksheets
for your students.  With some adaptation all of this stuff should work
nicely with your fifth graders.  Hit my NEWTON mail box if you have any
further questions.  I am an ex-EE teaching high school physics.  By
the way; these little generators break rather easily.  Make sure your
students do not try to crank them too fast and do not let them crank them
with the terminals shorted.  Have Fun!
Nick P. Drozdoff
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