December 09th, 2021

Exploring the circulatory system

Inspired by the children's interest and their questions about the circulatory system, we explored the human heart and how it works in the classroom. Through investigating and researching heart models and a variety of books on the topic, we learned about that the heart pumps blood through our body in special tubes, called blood vessels (for example veins, bringing oxygen-poor blood to the heart and arteries, bringing oxygen-rich blood back to the body). 

Did you know... 
... that 5 million red blood cells are in every drop of human blood?
... that the biggest arteries and veins are the width of a thumb?​
... that the total length of blood vessels (in an adults body) is 100,000 miles? That's four times around the earth!

Our circulatory system is so fascinating!

Lily: Kind of silly. It just doesn’t look like a heart.
(inspecting the small model of a human heart)

​Lucas: It’s fun! (What’s fun about it?) Lots of stuff. The inside of this is also cool. (What do you see on the inside of it?) I see spots and the blood. Like around here (small red part on inside of  the heart model)

Children's drawings and observations of the heart and blood vessels

Cate: This is the blood. What is the blue stuff supposed to be?
Lily: So the blue is when. So the red has the oxygen. Right? Right, Cate? And the blue has no oxygen.
Cate: Then what does the blue have?
Lily: It has nothing. I don’t know what it has.
Ines: The blood carries many things, like blood cells.
Lily: Blood can carry?
Ines: Yes, it’s like a river. It’s like a river going through your body.
Cate: I watched it on a robot show before and I saw blood cells. They were kinda like this shape, like a triangle shape, but a wavy one. And it was made out of fog and clouds and water. 

"inside of a blood vessel" by Finlay 

Lucas: I traced the heart. I'm curious about the heart. What is this hole? Red and blue lines. It's funny, these look like they turns into like water. Flooding through there.

​

Lily: I’m gonna use the outline in black. It’s supposed to be one side like blue and the other side red because there’s blue and red on there (pointing to the image in the book). Blue has no oxygen. How long does it take to go back to the heart? It’s going to your heart and then this goes out. It's the red one, when it had oxygen. But how does it the heart have oxygen in it?

Cate's drawing of a human heart, using red and blue yarn to create arteries and veins.

This is the real heart and
​this is the "I love you" heart. - Remy

This is what's happening RIGHT now!
- Daniel, excitedly holding his drawing of a heart and blood vessels in front of his chest to show the placement inside his body.

finding ways to explore the circulatory system on our own body

Cate: I see them on my arm!
Lily: Like those? (pointing to a wrinkle on her wrist)
Cate: I see them on my hand.
Ines: These are your veins. Your blood is going through them.
Lily: Some are darker, though. 
Cate: Blue! Mine, too.

Ines: Do you know you have blood vessels all over your body? Even in your nose, even in your feet.
Cate: Even in your ears.
Lily: And your eyes?
Cate: Look, like … (pulling down the skin underneath her eye)

To further investigate how the heart pumps the blood, we used a siphon pump, clear plastic tubes ("blood vessels") and "blood" (water mixed with blue water color). Our hand operated as the "heart", pumping the water from one bucket into the other.  We noticed that it requires great hand strength and endurance to operate the pump effectively and over a longer period of time (how many times can you pump in one minute?). Some children explored the effects alternating speed and frequency of pumping has on the process. 

​Hugh and Cape using the pump system
​
Hugh: This is so exciting! It looks like blood.This is the heart but you gotta squish it so it comes out the other side. Because then it will pump. (...) But how did you get the water to be blue?
Cape: This takes a long time. (to pump water from one bin into the other)
Hugh: It’s now getting harder and harder and harder. This bin is now almost gonna be full. The heart is pumping fast that’s why I’m pumping fast. I need to take a break.
Ines: Does your heart ever take a break?
Hugh: Probably when it’s like in the middle of the night it stops.
Ines: Can I tell you something? Your heart never stops, it always pumps.
Hugh: Until you die?
Ines: Yes. Every day, every minute …
Hugh: It pumps. Oh yeah, because blood makes you move. Because sometimes you move even when you’re sleeping, sometimes you roll in your bed.
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Bea and Frannie using pump system
​
Bea: It can beat quietly. The heart pumps the same night, every night and every day. It pumps the whole night, it pumps the whole entire day.
Frannie: It’s easy (to pump).
Bea: Well, when you have two hands on, it’s easy. And it pumps more water in the other one.

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​Michael and Daniel using pump system
​
Daniel: The water is going on to there. Because if he’s doing that (Michael, pumping)
the water will come in and in there and down there and going into that bath. It’s cool!

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Cape's drawing of "How the heart works"

​"It goes in circles. It goes the way I drawed it. It’s my heart. That’s the blood (blue). It’s pumping. Because when you squish it, it pumps (squeezing and releasing his fist). (The blood,) It moves!"

​​ indicating that the blood flows through the middle of the heart and the heart around it tightens