While working with shadows outside on a sunny day, many students will be surprised how fast they move. You may want to combine the shadow length measurements with investigations into shadow lengths and direction over time, focusing on the earth / sun system and the relative motions of the two bodies.
When working inside using light bulbs, please note that
they do get hot and can cause
burns.
The bulbs provided have power ratings of 40 watts or less
in the kits specifically to limit the heat they produce.
When setting these up please note that
clear bulbs with the simple v-shaped filament make sharp shadows
and frosted bulbs make fuzzy shadows. You will want to use
clear bulbs in the activity on measuring shadow sizes; note that
shadows are sharpest in the direction that sees the filament edge-on.
We recommend that you use the light stations provided in the kits - the plastic bases with porcelain sockets and pull chain. Screens can be boxes with white paper taped to the side or posterboard propped against a stack of books.
Next section: diffraction gratings.