The basics of light fall into 2 forms, reflection and refraction.
Refration (bending) is probably a little too much for 4-6 graders, but
reflection is easy and fun.
There are a few things that you can do with mirrors. A good place
to start might be with setting up a few mirrors and showing how light
can move around a book or something that is in the way, giving the
illusion of a whole in the book. I remember seeing that in a science
fair when I was in grade school and thought it was the coolest thing in
the world.
Related to that is a simply periscope. That is a good demonstration
of reflection and the children will think it's cool especially if they
know about submarine or spy movies.
The other thing that I can think of would be a little harder on you
equipment wise. If you could get a curved mirror, you could show them
how the light bounces off and that's why the image looks funny. The
inverted image that appears in a concave mirror might be a little too
much for them though.
Adam
(published on 10/22/2007)