Microscopes are used to observe microorganisms magnified. In light microscopy, the image is formed by a light source under the organism. We look through the so-called ocular, which looks like a small telescope, it serves a then-times magnification. The image is then magnified in different sizes by using different lenses so that even the smallest cell structures can be seen. The light microscope has the big advantage that it allows you to watch living structures.
Explanation for children: Microscopes are like special telescopes with which you can look at small creatures enlarged. In a light microscope, the living being sits on a plate, light comes from below and we can look at the living being from above. The light creates an image. With a light microscope you can look at creatures that are 100 - 1000 times smaller than a millimeter.