A microscope. The different parts of the microscope are identified. There is an inset picture of a something you might see with this instrument. As you look through the eyepiece with one eye, close your other eye. Use the coarse-adjustment knob to get the image nearly in focus. Use the fine-adjustment knob to bring the image into clear focus. The arm supports the lenses. The stage holds the object you are studying. The base supports the microscope.