I recently experimented using LED tap lights as an alternate to using stereoscopes in the Airborne Particulate Lab. You can read about the lab on this post. This is a great lab for kids to practice experimental design.
I purchased LED tap lights from Amazon but they can also be found at home improvement stores.
They work with a little finesse. Here is what the kids need to use:
Assemble like this:
Students need to focus on the vaseline above the grid. If they focus on the graph paper, they won’t see any particulates. They need to hold the hand lens about 3-4 centimeters above the petri dish. That way it focuses on the particulates.
This method does work, but it takes a little more practice from the kids to see the particulates.