Kids' Skeleton Facts

Updated April 17, 2017

The bones that make up the human skeleton are living tissues that grow and change. Much of this growth and change occurs during childhood as the child's skeleton develops into an adult skeleton.

Growth and Development

Some of the bones in a child's skeleton are made of cartilage. As children grow, bone tissue replaces the cartilage. Children's skeletons continue to grow and change until they are about 25 years old.

The Skull

Unlike an adult skull, the bones of an infant's skull are separate. The bones eventually grow together as the child develops and immovable joints hold the skull bones together.


A baby's skeleton is made of about 300 bones at birth. By the time a child reaches adulthood, many of the bones that were separate have fused together. As a result, the adult skeleton has only 206 bones.


Broken bones range from a hairline fracture to a complete fracture, where the bone is broken into two separate pieces. According to KidsHealth, a bowing fracture is a type of fracture that occurs only in children; the bone bends but does not break.

Bone Mass

In the Pediatrics article, "Physical Activity and Bone Measures in Young Children: The Iowa Bone Development Study," researchers correlated physical activity to bone-mineral density in young children ages 4 to 6. Children who were more physically active had greater bone mass than their less-active peers. Increased bone mass can result in fewer broken bones.

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About the Author

Alissa Pond Mentzer worked in biotech research and educational publishing before becoming a freelance writer in 2005. She has contributed to textbooks for The Mcgraw-Hill Companies and National Geographic School Division and writes science articles for various websites. Mentzer earned a Bachelor of Arts from Rutgers University in anthropology and biological sciences.