Place the magnifying glass on the surface of the mirror. Look into the center of the magnifying glass with one eye. If you wear contact lenses or glasses, you may either leave them on or remove them.
Adjust your distance from the mirror until you see a sharply focused and enlarged image of your eye. You may need to adjust the position of the magnifier to get the clearest image of your eye. Notice the white of your eye, the colored disk of your iris, and your pupil, the black hole in the center of your iris.
Shine a light into the pupil of one eye. If you are using a small mirror, hold the flashlight behind the mirror and shine the light around the edge of the mirror into your eye. If you are using a large mirror, bounce the flashlight beam off the mirror into your eye. Observe how your pupil changes size.
Notice that it takes longer for your pupil to dilate than it does to contract. Notice also that the pupil sometimes overshoots its mark. You can see it shrink down too far, and then reopen slightly.
Observe changes in the size of one pupil while you, or a partner, shine a light into and away from the other eye.
In a dimly lit room, open and close one eye while observing the pupil of the other eye in the mirror.