Your bones are alive. Bone is living tissue, and old bits of bone are removed and replaced with new bone all the time. 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 long bone does not grow from its middle outward. It grows at each end, next to a growth plate. Growth plates are the places where children's bones make new bone. A growth plate is made of cartilage, a rubbery material, and the tip of your nose is made of it too.

Growing does not go on forever. 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. Until then, the growth plates keep making new bone, so the bones can grow longer.

Nobody grows at a perfectly steady rate. Kids grow in spurts, with faster stretches and slower stretches. Some stretches are fast, and some are slow. Each child grows at their own pace. Doctors measure how kids grow and mark the numbers on a growth chart to follow growth over time.

Kids need healthy food every day to grow. A good plate has half vegetables and fruits. Healthy protein foods include poultry, fish, beans, eggs and nuts. Three things build healthy bones: calcium, vitamin D, and exercise. Calcium is a mineral, and milk, yogurt and cheese are among the best food sources of it. Vitamin D helps the body take in the calcium it gets from food.

Sleep helps kids grow, and growing bodies need the rest. Sleep comes in stages. Light sleep is easy to wake from, and deep sleep is hard to wake from. In deep sleep, the body releases hormones that kids need for growth. A school-age child who does not get enough sleep can have trouble paying attention.

How much sleep is enough? As of November 2026, kids 6 to 12 years old need 9 to 12 hours of sleep in every 24 hours. Kids 3 to 5 years old need 10 to 13 hours of sleep a day, including naps. Babies 4 to 12 months old need 12 to 16 hours of sleep a day, including naps.

Running, jumping and playing make muscles and bones stronger. As of November 2026, kids 6 to 17 years old need at least 60 minutes of active play every day. Those 60 minutes 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
• calcium: bone-building mineral
• hormones: body messengers
• tissue: body material
• spurts: quick bursts

The short version

Children grow longer at their growth plates, special spots near the ends of long bones where new bone is made. Growth is not steady, and each child grows at their own pace. Calcium, vitamin D, exercise, healthy food and enough sleep all help growing bodies.

Quick facts

• Growth plates are where children's bones make new bone, so the bones can grow longer.
• When a person is fully grown, the growth plates harden into solid bone.
• Nobody grows at a perfectly steady rate. Kids grow in spurts.
• Three things build healthy bones: calcium, vitamin D, and exercise.
• In deep sleep, the body releases hormones that kids need for growth and development.