You can build a laser microscope at home. I got the idea from a Make post. Back in 2001 a Slovenian scientist came up with the idea of shinning a green laser through a drop of water and projecting it on the wall. The roughly round drop of water acts as a lens.
This a simple educational project you can do at home or in any class room.
As you can tell I spared no expense in building my laser microscope.
List of materials:
1) Laser pointer (even a cat toy will work)
2) Syringe or Shish Kabob skewer (You just need something to suspend a drop of water.)
3) Projection screen (Which can be a wall, or like I did a piece of paper taped to a box)
4) Germ infested water (Fish tank water works great. I saw someone who used two day old beer left in a sunny window. I used the water squeezed from my kitchen sponge.)
5) It helps if you have a simple way to adjust the height of either the laser or drop (I used a broken toy microscope I bought at a thrift store to adjust the height of the syringe.)
This video kind of sucks, but it is just my very first attempt, and I plan to improve on it. It is just me holding a smart phone at an oblique angle. I think I can project the image directly on to the sensor of a web cam for better results.
What really scared me was just how much stuff was swimming around in the kitchen sponge I use to wash my dishes. Some of it might just be non-living particles, but I turned of all the fans and I think that stuff was swimming around on its own.