You probably know you need to eat protein, but what is it? Many foods contain protein (say: pro-teen), but the best sources are beef, poultry, fish, eggs, dairy products, nuts, seeds, and legumes like black beans and lentils. Protein builds up, maintains, and replaces the tissues in your body. (Not the tissues you blow your nose in! We mean the stuff your body's made up of.) Your muscles, your organs, and your immune system are made up mostly of protein.

Your body uses the protein you eat to make lots of specialized protein molecules that have specific jobs. For instance, your body uses protein to make hemoglobin (say: hee-muh-glow-bin), the part of red blood cells that carries oxygen to every part of your body. Other proteins are used to build cardiac muscle. What's that? Your heart! In fact, whether you're running or just hanging out, protein is doing important work like moving your legs, moving your lungs, and protecting you from disease.

There's fluoride in your toothpaste and even in your water. But how does it work to keep teeth healthy? Let's find out.

Fluoride is a natural element found in the earth's crust as well as in water and air. It's also considered a nutrient because our bodies need fluoride to grow and develop properly. Decades ago, scientists discovered that kids who naturally had more fluoride in their drinking water had fewer cavities. In the mid-1940s, communities started to put more fluoride in their water supplies to protect people against tooth decay.

Most nosebleeds look worse than they are. In other words, nosebleeds are messy, a little uncomfortable, and sometimes even scary, but they are usually no big deal.

Kids can get nosebleeds once in a while or more often. The nosebleeds that are most common in kids usually occur near the front of the nose, on the wall separating the two sides of the nose (the septum), and usually start from just one nostril. Sometimes nosebleeds start further back in the nose, but this is rare and occurs mostly in older people or those who have high blood pressure or injuries to their nose or face.

What Causes Nosebleeds?
Most nosebleeds occur when little blood vessels that line the inside of your nose break and bleed. These blood vessels are very fragile and lie very close to the surface, which makes them easy targets for injury. Common reasons are:

Why do some people need glasses and others don't? Everyone's eyes are a little different — not just the color, but the way they work and how well they see. Sometimes all the parts of the eye don't work together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most people see more clearly.

How Eyes Work
The eyeball includes the cornea (say: kor-nee-uh), clear tissue that helps the eye focus; the iris, the colored part; the pupil, which lets light into the eye; and the retina, at the very back of the eye. When all of the eyes' parts are working properly, a kid doesn't have vision problems. You can see because your eyes capture an image and send that image to your brain, where it can be interpreted. For instance, if there's an elephant in front of you, almost instantly, your brain says, "Hey, that's an elephant."

You wake up in a cranky mood. Your head hurts. You don't have the energy to even get out of bed. And you can't breathe out of your nose. What's wrong? You have a cold!

Having a cold is the number-one reason kids visit the doctor and stay home from school. Kids get up to eight colds per year with each cold lasting an average of 5 to 7 days. Let's find out more about them.

What Is a Cold?
A cold is an infection of the upper respiratory system. This just means it affects the nose, throat, and ears. A cold virus gets inside your body and makes you sick. There are over 200 viruses that cause colds. The rhinovirus (say: rye-no-vye-rus) is the most common cold virus, but there are more than 200 viruses that cause colds. Because there are so many, there isn't a vaccination, or shot, to prevent you from getting colds.

Fortunately, your body already has the best cold cure — your immune system. The immune system defends your body against illness. White blood cells are the immune system's main warriors. They're your own private army working to help you feel better. Take that, cold viruses!
How Kids Catch Colds