Hi Kelly! I work with a lot of tiny tiny creatures, and so I get to use microscopes a lot. I wouldn’t be able to identify my little creatures without the very useful focus wheel (or knob) as it moves the microscope stage (where my creature is sitting) up and down. There are two focus knobs, one for coarse and one for fine focusing. Without these my animals appear very fuzzy when I look through the lens. It also allows me to adjust to specimens of different thickness that are sitting on the same slide. Do you get to use microscopes in school? Hope that helps!