Safety:
Uses 95% ethanol, keep ignition sources away, keep slide projector 18 away minimum. Use caution in handling dry ice. Do not use ethanol twice for this demo but save the leftover for use in the elementary labs. Any disposal must be as hazardous waste.
Purpose:
There is no better way to give students a realistic feeling for the "facts of radiation" - that we're all constantly exposed to background radiation.
Notes:
Great for Open House nights, costs some money to run for the dry ice, the public really likes this one