GO IN DEPTH

# Bottled Model Lungs

#### Materials

• Clear 2-liter plastic soda bottles
• Scissors or knives
• Y-tubes
• String
• Latex gloves
• Rubber bands

Image Credit: Patrick J. Lynch, medical illustrator (CC BY 2.5), vie Wikipedia.

### Purpose

To build a model of the respiratory system and investigate the inputs, outputs, and interactions of the parts in the system.

### Context

Building models is an effective way to encourage new ways of exploring science, art, mathematics, and other subject areas. When kids become designers and builders—i.e., when they go beyond simply memorizing how the a-bone connects to the b-bone—they begin to understand the dynamic manner in which systems operate.

In this activity, students will learn about the respiratory system by comparing and contrasting models, building their own models, and giving one another feedback. According to the Benchmarks: “At this level, children can begin to view the body as a system, in which parts do things for other parts and for the organism as a whole. Models help children to see and touch the internal organs and to know where they are located in the body. Questions about familiar body systems can be useful in getting students to start thinking about systems generally. They can then begin to understand that each organ affects and is affected by others.” (Benchmarks for Science Literacy, p. 136.)

Students at this level have had limited exposure to the parts and processes involved in respiration. According to the research, “lower elementary-school students may have little knowledge about internal body organs and think the contents of the body are what they have seen being put into or coming out of it (food, blood). Upper elementary students can list a large number of organs; however, a sizable portion of adults have little knowledge of internal organs or their location (for example, few adults can draw the stomach and the liver in reasonable positions). (Benchmarks for Science Literacy, p. 344.)

Models help students understand parts and processes that are not visible, and help to demystify internal systems. According to the Benchmarks: “As students develop beyond their natural play with models, they should begin to modify them and discuss their limitations…. Students also can begin to compare their objects, drawings, and constructions to the things they portray or resemble (real bears, houses, airplanes, etc.)…. Students can begin to formulate their own models to explain things they cannot observe directly. By testing their models and changing them as more information is acquired, they begin to understand how science works.” (Benchmarks for Science Literacy, p. 268.)

Engaging students in collaborative activities is key to helping them understand why systems work, (or don’t work) and how properties change. A common misunderstanding for students at this level is that they think the properties of a system belong to individual parts of it rather than from the interaction of parts. (Benchmarks for Science Literacy, p. 262.) Hands-on modeling helps students understand cause and effect relationships, and how certain things must happen first in order for other things to happen next, (i.e., when you inhale, your diaphragm contracts to make room for your lungs, which fill up with air the way balloons do when you blow them up).

While doing this lesson, encourage students not to be intimidated by what they don’t yet know about respiration. The investigatory focus of this activity encourages students to tinker with inputs and outputs and in a sense “play” with putting together and taking apart parts, as a way of teaching them how to design systems.

### Planning Ahead

Note: As you’ll see, the websites used in this lesson contain introductory as well as rather in-depth information. Be sure to make it clear to students that the respiratory model they will build in this lesson doesn’t require all of the parts shown in the diagrams at the websites.

### Motivation

To begin, have an open-ended discussion to find out what students know about respiration.

Ask students:

• What do you know about lungs?
• What do you know about breathing and respiration?
• What are some of the body parts and elements involved in breathing? (Mouth, breathing tubes, oxygen, carbon dioxide, blood.)
• Have you heard of the respiratory system before?
• Why do you think it is called a system?

### Development

Designing Models and Systems

Distribute the Designing Models and Systems student sheet as a tool for students to record observations and feedback on their models. Explain to students that they will visit two websites to learn more about respiration as a prelude to building models. Pairing up students to work together is an effective way for students to share knowledge and observations. Remind students that the goal of the activity is to gain a broad understanding of models and systems, rather than a detailed recollection of the parts and functions of respiration.

As outlined on the student sheet, have students visit the website Inside the The Respiratory System. This site provides a basic overview on lungs and lungs as a system. It shows how lungs are made up of many parts and that all are important for the lungs to work right. Students who are less familiar with the respiratory system will appreciate seeing a concrete model of respiration prior to attempting to build one.

Also have students visit the website Your Respiratory System. This site provides a closer view of the lungs. Specific text on lungs, inputs, and outputs are mentioned (breathing in oxygen, breathing out carbon dioxide). This is important for the discussion of systems.

After visiting the second website, encourage students to use the student sheets to revise their first drawing and reconvene for a class discussion focusing on models and systems.

Ask students:

• How would you compare the first website model of respiration to the second model?
• Is one model better than the other? Explain.
• What is the difference between a model and a system?
• With what systems are you familiar? What makes these things systems? That is, how would you define a system?
• What is the function of this system (the lungs) as a whole? What are the essential parts of the system? What are the functions of these parts?
• Would the individual parts of the lung be able to function alone? Why or why not?
• Do you think it is important to have all the parts of the lung together in a certain way? Why or why not?
• Describe what each part does, and tell how each part contributes to the system as a whole.

Making Bottled Model Lungs

At this point, students should be ready to begin building their models. Hand out the Making Bottled Lungs student sheet. Students should continue to use the Designing Models and Systems student sheet to record observations and feedback.

After students complete their models, encourage them to seek out and provide feedback to one another. Research shows this is an important part of building students understanding of models and systems.

Following is an explanation of how the model relates to actual lungs:
When you breathe, your diaphragm contracts and expands. When you inhale, your diaphragm contracts to make room for your lungs, which fill up with air the way balloons do when you blow them up. The model demonstrates this action when you pull down on its latex bottom. When you exhale, your diaphragm expands, forcing the air out of your lungs. You can see this action using your model when you push up on its latex bottom. The muscles of the rib cage, which protect the lungs, are also used in respiration, allowing the lungs to fill up with air. The main purpose of respiration is the intake of air, which contains oxygen, an element vital to our survival, and the removal of the waste product carbon dioxide.

If time allows, students should view the Lungs & Respiratory System movie. This movie is useful in that it shows the in and out breathing movement that the students are simulating in their models.

Having begun this activity with a general idea of the process of modeling and respiration, this is a good opportunity to see what students have learned.

Ask students:

• What is the cause and effect relationship among parts? What is the relationship of parts to whole in a system? Between systems?
• How else could you model the lungs using household items? Explain.
• What other parts of the body could you model? How?
• How could you create a model of a heart?

Once students understand how the interaction of parts affects lung properties and functions in respiration, it will be easier to compare and contrast this system with other systems.

Ask students:

• How do systems interact and affect one another?
• In what sense are the lungs a system? In what sense are they a subsystem?
• How do outputs from one system become the inputs to another system? How are properties of the lungs affected by the inputs and outputs of the system?
• Discuss this statement: A system has properties that are different from those of its parts, but which only appear as a result of the interaction of those parts.
• Discuss this statement: The successful operation of a designed system usually involves feedback. Feedback is an important aspect of learning to build systems.

### Assessment

Once students have compared existing models, recorded observations, built their own models, and given one another feedback, it will be a good time to assess their knowledge.

Students should be able to name several body parts and processes associated with respiration, i.e., mouth, throat, lungs, breathing in, breathing out, oxygen, and carbon dioxide. They should have a basic understanding of models, and be able to identify common features of a system.

Ideally, kids might be able to “troubleshoot” and consider ways in which changing parts in a system will change its functions or properties. They should be able to make comparisons between human systems and other systems and understand that scientists, artists, and mathematicians all use models for similar purposes.

Ask students:

• What are two different types of models?
• In what way can your lungs be described as a “system”?
• What inputs, outputs, and interactions are part of the lungs system?
• What other systems are you familiar with?
• How do you know a “system” functions the way it is supposed to?
• What happens if one part of the “system” is broken? How does this affect the other parts and functions of the system?
• How does your model compare to real lungs?

### Extensions

The following Science NetLinks lessons can be used before or after this lesson to extend students’ understanding of models and systems:

Below are some additional websites with useful information about and models of respiration. Note: Some of the information at these websites is at a higher level and may be too advanced for some students.