You may have heard that bones grow from the middle outward, like a balloon. In fact, a long bone does not grow that way. It grows at each end, next to a growth plate. Growth plates are the places where children's bones make new bone, so the bones can grow longer.

Most long bones have two growth plates, one near each end. A growth plate is made of cartilage, a rubbery, flexible material. The tip of your nose is made of cartilage too.

Growth plates also explain why growing stops. When a person is fully grown, the growth plates harden into solid bone. After a growth plate has closed, that bone is no longer growing longer. A growth plate is weaker than solid bone, so it is easier to injure. Still, most growth plate fractures heal without changing how the bone grows later.

Bone is living tissue, and old bits of bone are removed and replaced with new bone all the time. Bones also hold calcium, and they release some of it into the blood when other parts of the body need it. The bone you build as a kid helps your bones for the rest of your life, because the most bone you will ever have is built when you are young.

Sleep is part of growing. Sleep helps kids grow, and growing bodies need the rest. In deep sleep, the body releases hormones that kids need for growth and development. Sleep comes in stages, and light sleep is easy to wake from while deep sleep is hard to wake from. As of November 2026, kids 6 to 12 years old need 9 to 12 hours of sleep in every 24 hours.

A third idea says that kids grow a little every day at the same speed. Nobody grows at a perfectly steady rate. Kids grow in spurts, with faster stretches and slower stretches. Doctors measure how kids grow and mark the numbers on a growth chart to follow growth over time. Babies are measured lying down, which is called recumbent length, and kids who can stand are measured with a stadiometer, a tall measuring device.

Some people believe that your height depends only on what you eat. Food matters, but genes have a large say in how a child grows, and children in a family often grow in similar patterns. Kids need healthy food every day to grow, and a good plate has half vegetables and fruits. Eating well supports growth, but eating extra food or extra vitamins does not make a child grow taller. Each child grows at their own pace.

Here is a myth about muscles. Eating a lot of protein does not build muscle by itself. Exercise is what increases muscle mass. Healthy protein foods include poultry, fish, beans, eggs and nuts. Younger children strengthen their muscles with gymnastics, jungle gyms and climbing trees, and most children do not need weightlifting programs.

Three things build healthy bones: calcium, vitamin D, and exercise. Calcium is a mineral that helps build strong bones. Milk, yogurt and cheese are among the best food sources, and leafy green vegetables such as broccoli, kale and collard greens also have calcium. Vitamin D helps the body take in the calcium it gets from food. Bone-strengthening activities include hopping, skipping, jumping and running, and kids should do them at least 3 days a week. Running, jumping and playing make muscles and bones stronger.

How much activity is enough? As of November 2026, kids 6 to 17 years old need at least 60 minutes of active play or exercise every day. The 60 active minutes a day do not have to come all at once. Walks, jump rope and playground time add up. Strong bones in childhood are a good start for bone health throughout life.

Words to know

• cartilage: rubbery body stuff
• recumbent: lying down
• stadiometer: tall measuring device
• tissue: body material
• genes: body instructions