Teaching Sequence

Work through this resource material in the following sequence:

10 minutes – Part A: How The Heart Works
30 minutes – Part B: Model Heart
15 minutes – Part C: Explaining High Blood Pressure
5 minutes – Reflection

Part A: How The Heart Works

Step 1.

Play this video explaining how the heart works.

How the Heart Works - Heart Foundation NZ (https://www.youtube.com/watch?v=GE0HlVTTgFc)

Step 2.

Explain to students that the heart is a muscle. Each 'pump' of the heart is a contraction of the heart muscle, squeezing the left ventricle to force blood through the artery. Like any muscle, it must remain strong to be able to push blood all the way around the body.

Step 3.

Play this video explaining blood pressure.

Blood Pressure Animation | Heart disease risk factors (https://www.youtube.com/watch?v=sOwBDmu1Y0c)

Part B: Model Heart

Note: This activity can be messy. You might like to complete this outside, or on a non-carpeted area, or put mats or sheets down prior to this activity.

Step 1.

Explain to students that you are going to make a model of a heart that will demonstrate the way the heart constricts the left ventricle chamber to force blood into the aorta and out into the rest of the body.

Label one bottle 'Heart'.
Label the other bottle 'Body'.
Take two bendy straws. Bend them at 90 degrees.
Slide one straw into the other, pinching the inside straw to make it smaller. Tape around the join.
Fill one water bottle with water about ¾ full. You might like to dye the water first with food dye to make it red.
Place the two ends of the conjoined straws into separate bottles, so that they form a bridge between the two bottles. The straw within the ‘heart’ bottle should be in the water.
Use Blu-Tack to seal the mouth of the bottles around the straws.
Firmly squeeze the 'heart' bottle and watch as the water flows through the straws and into the empty bottle.

This represents one beat of the heart. The muscle tissue around the heart contracts, squeezing the empty chamber in the heart, which is full of blood. This forces the blood out through the aorta into the organs, muscles and skin of the body.

When you release the squeeze on the ‘heart’, the bottle springs back into its original shape. This represents the second half of the heart’s beat, where the muscle tissue relaxes, allowing the chamber to expand and fill with blood again.

The heart can then beat again, pumping the fresh blood out into the body.

Step 2.

Now squeeze the 'heart' bottle more gently. Notice how not as much water is pushed through the straw bridge to reach the heart.

This represents a weak heart in a person with low blood pressure. The heart is not strong enough to push blood around the system of arteries in the body.

Step 3.

Explain to students they are going to alter the model to demonstrate a particular type of heart disease.

Remove the straw bridges from the bottles.
Pour the water back into the 'heart' bottle.
Fill one end of the straw bridge with Blu-Tack. Use a toothpick to make sure the blu tack is firmly pressed against the wall of the straw, but that there is still a small passageway open.
Replace the bridge in the bottles, with the restricted end in the 'body' bottle. Reseal the bottle mouths with Blu-Tack.
Simulate the heartbeat again.

Ask students to pay particular attention to the constricted end of the straw bridge. Notice how the heart is still functioning well and at full capacity, but the significant restriction in the aorta of the Blu-Tack means that all that blood is unable to make it out into the body.

Step 4.

Encourage students to squeeze the 'heart' bottle harder to try to get blood into the 'body'. They may end up rupturing the seal at the top of the bottle with their efforts, which is great, as we'll explain in the next part. Just be aware of the mess!

Part C: High Blood Pressure

Step 1.

After you have packed up the experiment, play this video explaining blood pressure.

How blood pressure works - Wilfred Manzano (https://www.youtube.com/watch?v=Ab9OZsDECZw)

Step 2.

Explain to students that in your model the Blu-Tack represents cholesterol clogging the tunnels of arteries in our bodies, preventing the blood from circulating easily. This can cause the heart to work harder to force blood through the tighter arteries, sometimes causing one type of heart attack, as seen by the bottle exploding.

Step 3.

Independently, students read the Blood Pressure Fact Sheet to further understand the impacts of cholesterol on the heart.

Step 4.

Independently, students create a poster, video or other piece of media explaining their understanding of high blood pressure and the risks it poses to health. The target audience could be older members of their family or community, as a way of informing them about the risks of heart disease and encouraging them to take preventative measures around their heart health.

Students may wish to film their heart model in action as an aid for demonstrating blood pressure, with a voiceover explanation.

Reflection

Invite students to complete the following written activity using the Student Worksheet:

What I learned today that was NEW:
What we discussed today that I already KNEW:
What I WONDER now:

Differentiated Learning

Extension - Do students have any personal connections with high blood pressure or heart attacks? Students could investigate these connections by interviewing family members. These stories can be powerful motivators for changes to eating and exercise habits in order to reduce the risk of heart disease.

Note: Be aware that such discussions could distress some students. Let them know you’re there to support them and to listen if they want to talk about it. Refer to the Handling Sensitive Topics and Issues factsheet for more information on how to support students.

Provisions for Learning Support - In Part C, you could talk through the Blood Pressure Fact Sheet with students and they could work in groups to create their informative piece of work.

Teacher Reflection

Take this opportunity to reflect on your own teaching:

What did you learn about your teaching practice today?
What worked well?
What didn't work so well?
What would you share?
Where to next?
How are you going to get there?

Jump Rope For Heart - Unclog My Heart

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