Background Information:
The main function of the respiratory system is to supply the blood with oxygen for the rest of the body. When a person inhales, oxygen enters the respiratory system through the mouth and nose. Next, oxygen passes through the larynx and trachea, the tube leading to the thoracic cavity
(chest). Now, this tube branches into two tubes (one leading to each lung) called bronchi. The bronchi continue to branch into smaller and smaller tubes, first bronchioles then alveoli which eventually become so small that oxygen can enter the blood through them. The diaphragm is a “sheet of muscles” which is located at the bottom of the chest cavity. When the diaphragm contracts, oxygen enters the lungs and when the diaphragm relaxes carbon dioxide is pushed out of the lungs. The contracting and relaxing of the diaphragm is called breathing (Oxygen Delivery System 1).
Materials:
 overhead transparency or plastic model of the human respiratory system
 6"x 4.5" (¼ sheet) piece of pink or gray construction paper (trachea)
 plastic 2-liter soda bottle with black bottom cut off (thoracic cavity)
 two round 9" or 12" pink balloons (lungs)
 two drinking straws (bronchi)
 medium-sized plastic bag large enough to fit over bottom end of bottle (diaphragm)
 3 or 4 cotton balls
 transparent tape
 medium-size, thin rubber band
Procedure:
1.
After going over the process of breathing and the parts of the respiratory system, ask for classroom volunteers to trace the path of air through the respiratory system on one of the visual models.
2.
Explain to students that they will be making a model of the respiratory system for each of them to practice on and better understand the process.

3.
Dismiss students in groups to gather the needed supplies from the stations.
 Before class, arrange all the needed materials in “stations” around the perimeter of the classroom. Above each station, include a well marked sign which states how many of each the student needs to take (for instance “take two straws”).
4.
Once the students have gathered all the supplies, have them follow you as you construct the model step by step. Watch carefully for students who may need help.
5.
After each step, have students hold their models up so you can visually check that each student is on the right track.
6.
Steps to build model: Insert straws into balloons and tape together at top. These are bronchi and lungs.
7.
Insert these through open bottom of modified 2-liter soda bottle straw end first and bring ends of straws up through the neck of the bottle.
8.
Stuff neck of soda bottle with cotton balls around straws until spaces are plugged.
9.
Roll construction paper into a tube just round enough to fit over the tops of the straws. Tape closed and place over tops of two straws.
This will be the trachea.
10.
Place plastic bag over bottom end of bottle and use the rubber band to hold it in place. This will serve as the diaphragm.
11.
Grasp bottom of plastic bag and pull down and push up. Watch as the
"lungs" expand and contract as you do this. Students may even bend
"trachea" and "bronchi" over so that the air supply is cut off and watch as nothing happens when the "diaphragm" is manipulated.
12.
Follow up with discussion questions.
(Diagram of model)

Discussion Questions:
1.
What is the main function of the respiratory system?
2.
Where does oxygen enter the respiratory system and what is this action called?
3.
Name three other parts of the respiratory system where oxygen passes through.
4.
What is known as a “sheet of muscles” and where is it found?
5.
What happens as the diaphragm contracts?
6.
What is the contracting and relaxing of the diaphragm called?
7.
How would you use this model to help explain the respiratory system to someone who knew nothing or little about it?
Extensions:
1.
Have the students go to another classroom (of the same grade) and each group take aside a group of students in the other classroom and explain the respiratory system using the model they just built.
Students can also take their models home and explain the respiratory system to their parents/guardians as homework.
2.
Have students write in their own words an explanation of their model to set along side it for Back to School Night. They might also write out the steps of making the model to go along with it also.
3.
Have students think of another way they might explain how the respiratory system works. Once they brainstorm an idea, have each group go to the front of their class and present their idea.
4.
Have students research another system and figure out a model idea for that system.
Teacher Notes:
 All of these materials can easily be obtained from asking students and their parents to donate supplies. This can be done a couple weeks in advance via a classroom newsletter. Any supplies not donated can be found at craft or grocery stores.
 Suggested readings –

The Respiratory System by Children’s Press
$7.88 at Amazon.com
The Respiratory System by Susan Dudley Gold
$23.93 at Barnesandnoble.com
** Science Standards:
Grade Five: Life Sciences 2a: Students know many multicellular organisms have specialized structures to support the transport of materials.
Grade Five: Life Sciences 2b: Students know how blood circulates through the heart chambers, lungs, and body and how carbon dioxide (CO2) and oxygen (O2) are exchanged in the lungs and tissues.

Works Cited:
“Adprima Lesson Plan” http://www.adprima.com/sci-respsystem.htm
“Oxygen Delivery System” http://www.fi.edu/biosci/systems/respiration.html