Edward Vakulsks, age 9, of Sioux City, Iowa, for his question:

Why do we blink?

Your eyes blink by themselves all day long and most of the time you do not notice it at all. Naturally there is a good reason for all this work. The blinking stops while you sleep because then the work is not necessary. Then your eyelids are closed to shut out the dusty air. The filmy air is always a bit dusty, even though the tiny floating fragments are far, far too small for your eyes to see. Your bright, shiny eyeball cannot abide bits of dust. Every time you blink, its eyelid comes down and wipes it clean. It works like a busy little windshield wiper.

A windshield wiper needs watery moisture to clean and polish the glass. And so does your eyelid. At the top, under the outside corner there is a spongy little factory that makes a special eye lotion. When you blink an eye, a drop of this super lotion squeezes out and the eyelid wipes it over your shiny eye. The used lotion washes down a tiny drain at the inside corner of the eye. The eye must stay moist and the salty lotion keeps it that way. It also contains soothing and germ fighting ingredients. And sometimes the little factory makes extra lotion that spills down your cheek in dewy teardrops.