Role-Play Work with a partner. Pretend you have to explain how the human body works to someone from another planet. Use information from the selection to explain the respiratory system. Use possessive nouns and technical terms.

Lungs pull in oxygen from the air and push out carbon dioxide. Below the lungs is a muscle called a diaphragm. It helps move air in and out of the lungs.

Study the Models When you write about people and actions, you want readers to understand whether you are talking about one person or more than one person. Make sure you communicate the right meaning to your readers.

Add Sentences Think of two sentences to add to the OK model above. Use possessive nouns correctly.

WRITE ON YOUR OWN Write about how a runner’s arms and legs move as he or she runs. Pay attention to your possessive nouns. Check them for correct spelling.

Spelling Rules

• 1. If there’s one owner, add ’s.

  Kim’s stomach is upset.

• 2. If there’s more than one owner and the noun ends in -s, just add ’.

  All the doctors’ offices were closed.

• 3. If there’s more than one owner and the noun does not end in -s, add ’s.

  The children’s lunches were full of healthy foods.

Remember

• • Possessive nouns tell readers who owns or has something.

• • All possessive nouns have an apostrophe (’).