Look at your nose. Snot is mucus, a sticky, slimy stuff the nose makes.

The clear, thin kind is healthy. Everybody makes it, even you, and that is perfectly fine.

It keeps the inside of the nose from drying out. That means it stays a little bit wet.

Think of the nose as a door. Dust and dirt try to come through it. Hairs in the nostrils help block big bits of dirt.

Snot catches dust and germs. They all stay out of the lungs.

Next come the cilia, tiny hairs. They wave back and forth all the time, like grass.

They sweep it, with what it caught, toward the throat. Off it goes.

Then we swallow it. In the stomach, it meets acid. That helps destroy the bad stuff in it.

A booger is dry snot. It has bits of dust, pollen and dirt in it.

Boogers have lots of germs. Picking can make the nose bleed. A tissue is a better tool. It traps them when you blow.

Wash your hands with soap and water. About twenty seconds is a good length. Count slowly to twenty, and you will get it right.

So here is the plan. The nose catches dirt, and the hairs sweep it away. That is the whole plan.

Words to know

• mucus: nose slime
• cilia: tiny hairs
• pollen: flower dust
• tissue: nose wipe paper
• nostrils: nose holes