Introduction to The Circulatory System

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SWBAT to identify major components of circulatory system along with describing their function.

Big Idea

Students learn about the circulatory system by developing a model.


5 minutes

To engage students I have them read the following statement.

A City of Cells

Think of your body as a city of cells. Each cell is like a house. A house needs fuel, energy, water, and raw materials. A house must also have a sewer system and garbage pickup to get rid of wastes. Your body must take in needed materials and get rid of waste materials just like a house does.

Once students have read the statement, they complete a Journal Writing in their science notebook.

Journal Writing (5 min)

What makes a delivery system efficient? Imagine you are in charge of a package delivery service. What things might make your job harder? What things might make your job easier? What would be the most important parts of a successful delivery company? Write a paragraph to explain your ideas, and include any lists, diagrams, or drawings that help your explanation.

The objective of the journal writing is for students to begin to start thinking about efficient delivery systems.  In this lesson students will be introduced to our delivery system, the circulatory system. (MS-LS1-3 body is a system of interacting subsystems composed of groups of cells./CCC - Systems and System Models -Systems may interact with other systems; they may have sub-systems and be a part of larger complex systems.)  

After writing, students volunteer to share their writing with the class.  

I end this section of this lesson by telling students that we have a delivery system in our bodies that is as efficient as it's important.  I show them the picture below and tell that that we they will be introduced to the circulatory system in todays lesson.


We take a moment to look at the meaning of the image.  Your circulatory system is like the streets of a city, with lots of traffic flowing through the streets to and from different destinations.


25 minutes

In this section of lesson students begin to explore the structure and function of the circulatory system by developing a model.


In this activity you will learn about all the parts of your circulatory system and what they do. Let's start by building a model that can serve as your guide to the parts of the circulatory system and how they fit together. (SP2 Developing and Using ModelsDevelop a model to describe unobservable mechanisms.) 


  • Paper cups (4)
  • Straw
  • Glue
  • Paper towels
  • Colored pencils, pens, or paint (blue and red)
  • Tape
  • Balloon (white)
  • Colored thread (blue and red)
  • Colored yarn (blue and red, 2 pieces 20cm each)
  • Lima beans (3 or 4)
  • Scissors
  • Ruler


First, you are going to build a model heart. The heart is two pumps side by side. Each pump has two chambers. In both pumps, blood enters the upper chamber and leaves the lower chamber. So you will have four blood vessels attached to your heart model. Now follow Steps 1 through 6 as you build your model heart.

Use a pencil to carefully make a hole in each cup. You will place straws in the holes in the heart model. The straws will represent blood vessels.

Step 1 Place the open ends of two paper cups together. Secure the cups together with tape. Do the same thing with the other two cups.

Step 2 Stand the two sets of cups side by side. Each cup represents a heart chamber.

Figure 1.2 

Step 3 Carefully poke a hole in the side of each cup as shown in Figure 1.2 above.

Step 4 Cut a straw into four equal pieces. Color or paint two of the pieces blue and the other two pieces red, (You'll find out what the colors mean later.)

Step 5 Insert and glue one of the blue straws into opening B. Insert and glue a red straw into opening C.

Step 6 Stick a piece of blue yarn into the open end of the blue straw attached to the cups. Stick a piece of red yarn into the open end of the red straw attached to the cups. The straws and yarn represent blood vessels corning to and leaving the heart

Now you have two halves of what will be your model of the heart. The straws and yarn represent the system of blood vessels through which the heart pumps blood. Remember that this model resembles a figure eight rather than a simple circle. Half of the figure eight is the lung circuit where blood picks up oxygen. The other half of the figure eight is the body circuit where blood gives oxygen to all the cells of the body. Now you know the significance of the blue and red colors. Blue represents vessels carrying blood after it gives oxygen to cells. Red represents vessels carrying blood with a full load of oxygen. You can use this information in completing the following steps to finish your model.

Step 7 Inflate a white balloon to about 10cm (4 inches) in diameter and tie it off. The balloon represents the lungs.

Step 8 Glue blue and red threads on the surface of the inflated balloon, or use pens to draw blue and red lines. The threads (or colored lines) represent the tiniest blood vessels where the blood picks up oxygen from the air in the lungs.

Step 9 Glue the free ends of the blue yarn to the surface of the balloon that has the tiny blue vessels. Glue the free ends of the red yarn to the surface of the balloon that has the tiny red vessels. You have completed the part of the model that represents the pump that moves blood to your lungs and back to the heart. This part of your completed model should look like the one in Figure 1.3.

Step 10 Now finish your two-pump model of the heart by making a model of the pump that moves the blood to your body cells. Insert and glue the other red straw into opening D. Insert and glue the other blue straw into opening A.

Step 11 Stick a piece of red yarn into the open end of the second red straw. Stick a piece of blue yarn into the open end of the second blue straw.

Figure 1.3 This is how the two halves of your model heart should look.

Step 12 Obtain three or four lima beans to represent body cells. Cut about 10 to 12 pieces of thread, each about 3 centimeters long. Half of the pieces should be red. The other half should be blue. Glue one end of several red and blue threads on the surface of each bean.

Step 13 Attach the free end of the red threads to the red yarn. Attach the free ends of the blue threads to the blue yarn. Your completed model should look like the one in Figure 1.4.

Step 14 Be sure you can explain to someone the path that a drop of blood would take in flowing through your model.  Then write an explanation of how the blood would flow through your model.

Step 15 Write your name and the date on your completed model.

Step 16 Check with your teacher for cleanup instructions and to find out where to store your model.



10 minutes

In this section of the lesson I show students an animation, which discusses the three main components of the circulatory system (blood, blood vessels, and heart). Animation does a great job of explaining how all three parts depend on one another to create an efficient system. 

As students watch the video, they answer the following questions:

1)  The red blood cell ride the highways of the _____________ _____________.

2)  What shape comes to mind when you hear the word circulatory?  

3)  What circulates around our bodies everyday?

4)  What is the name given to the small "tunnels" found in our bodies?

5)  What do arteries carry?  What do veins carry?

6)  How does our blood move?

7)  At least how many times does your heart beat?

8)  Name all the "rooms" found in the heart.

9)  What do red blood cells need to pick up before making deliveries?  Where do they pick up this package?

10)  What color does the red blood cell change to after it's dropped oxygen? 

11) What does the red blood cell pick up after it's dropped off all its oxygen?

12)  Where does this new package end up in? What do you think the lungs do with this package?

Note: The reason I chose this video over one that goes into more detail is that this is an introductory lesson to the circulatory system.  Each of the components will be discussed in more detail in other lessons in unit.


10 minutes

In this section students complete an animation module courtesy of PBS Learning Media. 

Cellular Service

In order to survive, every living cell in the body needs a constant supply of oxygen and nutrients and needs to have wastes removed. In the Web activity Cellular Service , students follow a small sample of blood as it travels throughout the body. The goal of the activity is to keep a few cells, located in an extremity of the body, alive and healthy.

Once students have completed Cellular Service we have a small discussion over the questions below. 

Discussion Questions

  • What are some of the many functions of blood?
  • How does the blood distribute what the body needs?
  • What needs are met by oxygen? Nutrients? Enzymes? Bacteria? Hormones?


10 minutes

In this section of lesson students begin to start working on a Exit Slip where they are required to create a presentation on the circulatory system.  The focus of the presentation is how blood receives and carries oxygen throughout the body. (SP8 Obtaining, Evaluating, and Communicating Information)


1.  Relationship between heart, lungs, veins, and arteries.

2.  Show the path that blood takes throughout the circulatory system.