Living things change as they grow.How is the kitten like his mother?How is he different?How does a little children changed since he was a baby?
Someone is getting taller because his bones are growing.You can’t see your bones grow.All you or anyone else can see is that your body has grow taller.
When you were born,do you think most of your bones were hard or soft?It was soft.But,when most of your bones were soft,they were called cartilage.Little by little,most of the soft cartilage was changed into hard bone.
Perhaps you have been able to watch a puppy or a kitten grow during its first year.If you have,you probably noticed different signs of growth.One sign of growth that you probably noticed was that animal grew larger.Animals are able to grow larger because their bones are able to grow.
One of the ways a bone grows is longer.A bone is able to grow longer because it has special growth places.These places are near the ends of the bone.Growth places are made of cartilage.In order for the bone to grow longer,the part of the cartilage next to the bone slowly changes into hard bone.At the same time,new cartilage forms at the tip of the old cartilage.As time goes by,more of the cartilage next to the bone becomes part of the bone.Also,more new cartilage forms at the tips of the old cartilage.As this keeps happening,the bone grows longer.
Growing longer is not the only way bones grow.Bones also grow thicker.Bones grow thicker by forming new layers of bone on top of their outside layer.People’s bones grow in length and in thickness until they are in their late teens or early twenties.
Bones grow together
Some of your bones,however,grow and change in still another way.These bones change in still another way.One part of your body that has bones that have grown together in this way is your skull.Your sacrum is another part where the bones have growth together.
Think the ways that Superman and Wonder Woman are alike.One of these ways is their great strenght.The thing that makes them strong is their muscles.You have muscles too.You of course,can’t do the same things these make believe people can do.But,yuo do have strength.And the thing that makes you as strongs as you are is your muscles.
Like your bones,your muscles grow.And like your bones,your muscles grow as you grow.Muscles are made of muscle tissue.The muscles that give you strenght of muscle tissue.Such muscles are in your arms,legs,and back.Certain other parts of your body are also made of muscle tissue.Your heart and your stomach are two such parts.As you grow,your body makes new muscle tissue.
Therefore,as you grow bigger,your muscles grow bigger.This will happen as long as you eat the right kinds of food and get the rest your body needs.But your muscles need more than food and rest to grow bigger and stronger.Your muscles also need to be used.When someone run and play certain games,they are using their muscles.The more exercise,or work,the muscles do,the stronger they become.You can get some exercise everyday just by doing things you like to do.But you must continue to work your muscles hard for at least 15 minutes at a time.Running,walking fast,and jumping rope are all good exercises to help make your muscles strong.If you stop exercising as soon as you feel a little bit tired or do not exercise everyday,your muscles may not get enough exercise to be strong.They may even be able to stay as strong as they are now.