This is a lensless microscope that uses a drop of water as the lens. Organisms in that drop of water would be magnified and projected on to a wall or other surface. This is an easy to assemble microscope that only requires a laser pointer, syringe, needle, stand, and projection surface (wall or ceiling). More info here.
(posted to youtube by Sally Le Page, November 6, 2015)
See the drop microscope in action (posted to youtube by Adam Smasher, July 17, 2010):