You slip on the playground and scrape your knee. Ouch! Any cut, scrape or scratch that breaks the skin is called a wound.

Your skin does a big job. It keeps germs out of your body. When skin breaks, germs can get in, so a wound needs care.

First, wash your hands with soap and water. Then rinse the cut with clean water to wash the dirt away. Tell a grown-up about it.

Even small cuts and scrapes need to be cleaned and covered so they do not get infected. A bandage covers a small cut and keeps it clean while it heals.

Soon your body makes a scab. A scab is a hard crust that forms over a cut or scrape. It is like a little shield that helps keep germs out.

Under the scab, your body builds new skin. The scab can itch while this happens. Scratching it can break the new skin.

It is hard, but do not pick a scab. Picking a scab makes a cut heal more slowly.

Not every cut makes a scab. A cut that is kept moist and covered may not form one.

Small cuts heal faster than big, deep ones. Most minor cuts are healed in a week or less.

When the skin underneath has healed, the scab falls off by itself.

Sometimes a mark stays behind. A scar is a mark that is left on the skin after a wound has healed. Most scars fade as time goes by.

Watch for signs of trouble. Spreading redness, more pain, swelling or pus are signs of infection. If you see them, tell a grown-up. A grown-up should call a doctor.

Words to know

• wound: a hurt skin
• scab: a crust
• scar: a leftover mark
• infected: filled with germs