Alright so compound light microscopes work by putting light through many bent glass lenses to sort of distort light and zoom in on objects. TEM's work by bombarding an object with electrons and capturing those that come back and analyzing what returns as data. It has to do with the speed angle and time it takes the electron to get back to the sensor to make an image. TEMs are far more capable at zooming in on super tiny objects than their light based counterparts but are also exponentially more expensive. I would not expect to find one in your high school.
