The Respiratory System

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SWBAT identify the structures of the respiratory system and describe their functions.

Big Idea

This lesson provides students with a hands on opportunity to explore the role of the diaphragm in the respiratory system.


5 minutes

The students enter the room and take out their journals in order to respond to the prompt: How is the respiratory system connected to the muscular system?  Explain.

In a previous lesson we discussed the muscular system and prior to this class period the students were to have taken notes about the muscular system, so they have the information they need to answer this prompt successfully, though it will require them to combine what they know about the two separate systems.  By responding to this prompt, we are addressing NGSS Crosscutting Concept Systems and System Models - systems interact with other systems and can be part of larger complex systems - because the students are explaining how the respiratory and muscular system interact and function as a part of the body.

As the students write, I circulate through the room to review their responses.  During this time, I ask some students to elaborate on their explanation while I help others determine the connection between the two systems.

Once the students have had a chance to write down their thoughts, I ask for volunteers to share their responses with the class.  While the students share their ideas, I use the LCD projector to display a diagram of the respiratory system and point out the diaphragm.  We refer to the diagram as we review the function of the diaphragm, specifically how it moves and what happens to the the lungs as it moves.   

This is a proficient student journal sample.


15 minutes

Prior to this lesson the students took Cornell notes from the reading on the Respiratory System Organs, from cK-12. The students also completed the review questions as homework.

I lead the students in a review of the notes by asking them to explain the structures of the respiratory system and the functions of each structure. We begin by discussing the nose and I ask the students if the nose is associated with any other body system. The students are able to recognize that the olfactory cells in the nose help to connect it to the nervous system. As we review the other parts of the respiratory system, I move through this Respiratory System Presentation, to provide students with additional visuals of the structures we are discussing. I also use the presentation to remind the students of the difference between respiration and breathing.  We discussed respiration at the beginning of the year, so this is a great opportunity to review the information with the students to help ensure retention of the material. Our review of the presentation addresses NGSS MS-LS1-3 - Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.

After we have reviewed the notes, students complete a bulletin board labeling activity. I have placed a blank respiratory system diagram on a bulletin board and I give each group one labeled notecard. The labels on the notecards are nasal cavity, trachea, pharynx, larynx, primary bronchi, and lungs. Group members are given a couple of minutes to discuss and reach consensus about where their notecard should be placed on the bulletin board. I then ask the class where air enters the respiratory system and ask the group that has the correct card to bring it up and place it on the board. I continue naming the function, awaiting students identification of the "form" as we work our way to the lungs.  Here is a picture of the completed respiratory system bulletin board.


15 minutes

After reviewing the various structures of the respiratory system, I ask the students to open the Respiratory System Model Worksheet while I load it on the LCD projector.  I go through the instructions with the students, pointing out that the directions for creating their model will be found in their textbook.  There are several different types of lung models that can be made in the classroom.  

The model used in this lesson is similar to the model shown in this video.


The model my students create requires two balloons and one clear plastic bottle.  I start with this basic model with the intent that students will modify the model to include a trachea, another lung, etc.  Creating the model in this lesson helps the students better understand the role of the diaphragm in the respiratory system and addresses NGSS SP2 - Developing and using models.

Once we have reviewed the lab instructions, I use a modified version of the Line Up strategy to place students in their lab groups.  I give each student a notecard that has the name of one of the respiratory organs and have them form groups by finding one of each of the structures in the respiratory system.  This ties directly to the respiratory system bulletin board activity and to the first question on the respiratory system model worksheet, creating a repetitive review of the structures of the respiratory system.  In order to enter the lab and begin working, the students check in with me to make sure that their group contains the correct structures.  If the group is not correct, I send them back to try again.

In the lab, the students answer the first question and are then able to begin building their model.  I have a wide variety of recycled materials available for the students, so they are able to select the plastic bottle they would like to use.  I have found that small juice bottles work very well for this activity.

While the students work on their models I circulate through the room, asking the students to explain their answers to the questions on the worksheet.

For instance, after reading this student response I ask the students to explain what they mean by deplete and if only oxygen and carbon dioxide enter and leave the lungs.

Before you make a model, describe how the respiratory system works.  What organs/structures are involved?  How does air travel through the system?

Air enters the body either by the mouth or by the nose. If it goes through the nose, the mucous in the nose moistens the air, and the nose hairs in the nose collect particles of dust, and other debris, and stops it from entering the lungs. Once it has gone past the mouth or nose, it goes down the pharynx in the throat till it gets to the larynx, or windpipe. Once there, it goes down the trachea to the bronchi. The bronchi branch out like trees to the alveoli which is the part of the respiratory system that actually hands off and receives gasses. The alveoli are in the lungs, the major organ of the respiratory system. it gives oxygen to the blood and receives from it carbon dioxide through diffusion. Then the carbon dioxide goes back up the respiratory system to leave the body. The way that the lungs expand and deplete and change pressure is by the diaphragm rising and lower.  

I also assist the students in making their models in terms of cutting the plastic bottles for them and helping them troubleshoot ways to get their balloons to stay on the bottle.  When their models are finished, I ask them to describe their models and explain how they work.

Wrap up

5 minutes

At the end of class I have the students clean up their areas and I ask a group to demonstrate their working model for the rest of the class.  While the model seems simple to build, I do have some students that struggle with it, so I recommend having a premade model ready to use for this part of the lesson.  While using the demonstration model, I ask the students to describe what the parts of the model represent and to describe the process being modeled. 

As we explore the model, I ask the students to share their ideas from the last question on their worksheet: What modifications can you make to your model to make it more representational of the respiratory system?   

I am looking for the students to explain ways in which they could add to the model to demonstrate the other parts of the respiratory system.  This is the type of student response I am looking for: If we made the balloons larger, it would make the action and movement more accurate. It would also be cool if we could connect a nose somehow and blow air through so it looks like a nose and lung combo. We could not make the changes because we did not have the larger balloons.

By asking the students to explore ways to improve their models, we are addressing NGSS Crosscutting Concept Systems and System Models - Models are limited in that they only represent certain aspects of the system under study.