• was successfully added to your cart.


Lesson 11 – Good bones

Read About Your Bones


Read the vocabulary terms to understand the reading better.


Calcium is a mineral found mainly in the hard part of bones.


Cartilage is a firm, flexible, elastic type of connective tissue in the body.


Minerals are a natural element, or substance, from the ground that is present in food and is needed by our bodies to grow and function properly.


A skeleton is the hard internal structure that supports and protects the soft organs, tissues, and other parts of a vertebrate organism, and is made up of bone and cartilage.

Vitamin D

Vitamin D is a vitamin that is very important for the healthy growth of bones and teeth; vitamin D is found in fish-liver oils, egg yolks, milk, and sunshine.

Good bones

Your skeleton is your body’s framework. This means it gives your body shape. It helps support different parts of your body. It helps protect what is inside your body, such as your lungs. Think about what your body would be like without a skeleton.

Your skeleton is made up of many different bones. These bones work together so you can move in many different ways. So it is important that your bones are healthy.

How Bones Change

Your bones are a living part of your body. When you were born, you had about 300 bones. Some baby bones are made from cartilage. Other baby bones are partly cartilage. Cartilage is softer than bone. That is why babies are so flexible. They can move their bones in ways that adults cannot. As a baby grows, the cartilage is replaced by bone, and some of the bones grow together. At around the age of 25, a person’s bones stop growing. At that age, the adult skeleton has 206 hard bones.

Ears are made of cartilage

Calcium and Bones

Calcium is a mineral. It is what helps bone grow to replace cartilage. It helps make bones strong. Calcium is very important when you are growing. Because bones grow for a long time, it is important for children and teenagers to get all the calcium they need. The most common source of calcium is milk. You can also get it from other dairy products such as cheese and yogurt. Calcium is also in dark green vegetables such as broccoli and kale. Some foods have calcium added to them. These are called calcium-fortified foods.

For calcium to work in your bones, it needs vitamin D. Your skin makes vitamin D when it is in sunlight. A small amount of vitamin D is found in fish such as salmon or tuna. Some foods, such as milk, are fortified with vitamin D.

Activity and Bones

Parts of your body, such as muscles, become stronger with exercise. Bones also get stronger with the right activity. The best activities to make bones stronger are called weight-bearing activities. These are activities in which you work against gravity, for example, walking, hiking, playing tennis, and lifting weights. Swimming and bicycling are good exercise, but not for your bones.

Many doctors think that the right exercise is just as important for making strong bones as calcium is. So make sure you get enough calcium and do the right activities for your bones. They have to last a lifetime.

Now Show What You Know!

Complete some questions about the reading selection by clicking “Begin Questions” below.