How the Lungs Work

Science · The Human Body · ages 9-11

Name ______________________ Date ____________

Look at the pathway. Which part comes right before the alveoli?
- Bronchi
- Bronchioles
- Trachea
After air enters your nose or mouth, where does it go next?
- Straight to the alveoli
- Down the trachea
- Into the diaphragm
The alveoli are tiny air sacs where gas exchange happens.
Circle one: True False
Why does the diaphragm contract when you breathe in?
- To push air out of the lungs
- To pull air into the lungs
- To turn oxygen into carbon dioxide
What happens to oxygen when it reaches the alveoli?
- It stays trapped in the air sac
- It passes into the blood in tiny capillaries
- It turns into carbon dioxide
Put these in the right order: bronchi, alveoli, bronchioles. What comes first?
- Bronchi
- Alveoli
- Bronchioles
If the bronchioles were blocked, which part of the lungs would air have trouble reaching?
- The nose
- The trachea
- The alveoli
Jake says carbon dioxide passes into the blood at the alveoli, and oxygen passes out. What did he get wrong?
- He has it backwards: oxygen goes in, carbon dioxide goes out
- He is completely correct
- Neither gas moves at the alveoli

Answer key

For grown-ups. Fold this page away before handing over the rest.

Bronchioles · Bronchioles are the tiny tubes that lead straight into the alveoli.
Down the trachea · Air travels down the trachea before it reaches the bronchi and bronchioles.
True · That's exactly where oxygen and carbon dioxide swap places with the blood.
To pull air into the lungs · When the diaphragm contracts, it makes room in your chest so air rushes in.
It passes into the blood in tiny capillaries · Oxygen moves from the air sac into the blood vessels wrapped around each alveolus.
Bronchi · Air passes through the bronchi before it reaches the smaller bronchioles and finally the alveoli.
The alveoli · The bronchioles are the last tubes before the alveoli, so a block there stops air from reaching the air sacs.
He has it backwards: oxygen goes in, carbon dioxide goes out · At the alveoli, oxygen moves into the blood and carbon dioxide moves out, the opposite of what Jake said.