Listen To Your Heart

How many times does your heart beat in one minute?

Children’s bodies are undergoing constant change. By getting to know their own bodies better, these changes can be less mysterious. Children who are in tune with their own bodies can use all of their senses as tools as they explore and try to understand the world around them. This activity will help children to get better acquainted with their heart rate.

Preparation

See Suggestions under “Make it Better” for information on where to fund funnels and tubing.

Cut the plastic tubing into pieces and 18″ long. You don’t have to be exact. You’ll need 1 piece of tubing for each child. Make a stethoscope to show your students – hold a balloon by the open part and cut it in half, a little bit past the area where the neck widens. Discard the half you usually blow into to inflate the balloon. Stretch the remaining half of the balloon across the wide part of the funnel – make sure it’s nice and tight (see figure 1 for an illustration).

Resources

Figure 1

Suggested Materials

Small plastic funnels (see Preparation) (one for each child)
1/4-inch inner diameter flexible plastic tubing (18″ per child) (see Preparation)
Helium quality 9″ balloons (50)
Scissors
Stopwatch or lock with a second hand

Opening Discussion

Ask your students if a nurse or doctor has ever listened to their heart during a check-up or hospital visit. How did they do it? Did they use any special tools? What was the doctor doing? Do your students each know how many times their own heart beats in 1 minute?

The Challenge

Make your own stethoscope and measure how many times your heart beats in a minute!

Doing the Activity

Show your students a completed stethoscope. Demonstrate the process for making their own.
Hand out the materials and monitor your students as they make their stethoscopes. You may need to help them stretch the balloons across the funnels.
Once everyone has their stethoscope made, challenge them to find their heartbeats.

Let’s Talk About It

After 5 minutes of activity, when some of the children have found their heartbeat, stop your students and bring them together to share their observations with each other. Where did they place the funnel on their chest? Does anyone have any other tips for using the stethoscope? This discussion should only last a few minutes.

Build On What They Talked About

Once everyone can hear their heartbeat, ask the entire class to be quiet, get their stethoscopes ready and on your signal, count their heartbeats. Time 1 minute, and then have everyone write down their heart rate. Ask your students if they think their heart rate is always the same. What will happen if they jump up and down for 2 minutes, then test their heart rates? What if they lay down and close their eyes for 2 minutes? What if they run around? Have them try all different sort of activities and measure their heart rates.

Suggestions

Try showing your students how to find their pulse on their wrists. Is this easier or harder than using the stethoscope?
Funnels can be found in some hardware stores, though usually in a size too large for this activity. The best option for funnels that we’ve found is from Globe Scientific (click here to visit their website). Search for “disposable funnels”, and select the 55mm polypropylene funnel. These funnels come in cases of 100, and cost about 30 cents per funnel.
Flexible plastic tubing can be found in aquarium supply stores and some hardware stores. Visit McMaster-Carr (click here to visit their website) if you wish to purchase tubing online. Definitely go with the “Masterkleer” PVC tubing – it’s inexpensive (20-30 cents/foot) and works well. Click here for the product page for the correct type tubing. Select the 1/4″ inside diameter; 1/16″ wall thickness; and clear tubing.
McMaster also carries funnels, though they cost more than the suggested vendor above. If you prefer to order funnels and tubing together from McMaster, you will need different-sized tubing from that suggested above. Order part number 4383T1 for the funnels (click here for the product page). Look for the “Economy Vapor-Lock-Resistant Funnels”. The Polypropylene, 2 oz Cap, 2-11/16″ Top OD for 80 cents each is the right one. If you order this funnel, you’ll need flexible tubing with a 3/8″ inner diameter. You should still get the “Masterkleer” PVC tubing. Select the 3/8″ inside diameter; 1/16″ wall thickness; and clear tubing.
What is the average heart rate for the entire class in beats per minute (bpm) (add all of the heart rates up, then divide the total by the number of students in the class)? Below are some other average heart rates for comparison. Is there a pattern between animal size and heart rate?

Cat – 150 bpm
Bat – 750 bpm
Guinea pig – 280 bpm
Skunk – 166 bpm
Dog – 90 bpm
Mouse – 534 bpm
Horse – 44 bpm
Squirrel – 249 bpm
Hamster – 450 bpm
Chicken – 275 bpm
Giraffe – 65 bpm
Adult human – 60 bpm