OceanMan7 writes "My 7-year-old son is getting very interested in microscopic things — from bacteria to parameciums (paramecia?) Not being a biologist, I would appreciate advice on what type of microscope to get. I'd be operating it and he viewing with supervision. I'd like something better than a toy and plan to buy it used, if possible. Extra points if it's stereo and also allows me to view opaque objects at low magnification."