Stethoscope

Grade: 4 and 5

Objective: In this fun hands on lesson, students will explore their heart beats and learn about blood circulation. They will make their own stethoscope, use them to measure their heart rates and investigate how heart rate is affected by exercise.

Group: 2 students per group

Basic introduction:

A stethoscope is an acoustic medical device for listening to the internal organs of human body as well as animals.
It consists of: Ear tips, Ear tubes, Tubing and Chestpiece.

The chestpiece has a diaphraghm for listening to high frequency sounds and a bell for listening to low frequency sounds.

Key questions to ask :

What is stethoscope used for?

What sound does the human heart make?

How does exercise change the sound of heart?

Explaination

Did you know that when a doctor listens to your heartbeat with a stethoscope, they are actually listening for two sounds? The first sound is a longer, lower pitched sound. The second is a shorter, higher pitched sound.
The lower pitched sound is made by the closing of two heart valves when blood is flowing out of the heart. The higher pitched sound is made by two other valves when blood is flowing into the heart. When a person exercises or participates in any kind of physical activity, the heart beats faster in order to pump more blood and oxygen to the muscles that are being used. The closing of the heart valves makes a sound which causes the stretched balloon to vibrate. The vibrating balloon makes the air in the tube vibrate and the tube then carries these sound vibrations to your ear.

1. A metal wire of length half meter (The diameter should be such that it can easily bend)

2. Tubes

3. Ear tips

4.Push fit T connector

5. Plastic cup

6. Balloon (1)

7. Scissor

1. Take a metal wire and bend its both end by 90 degree as shown in the image.

2. Take a push fit connector of Tshape. In the video it has been shown how to use it. It is a pneumatic device which ensures that there is no leakage of air while it is connected with the rest of the parts.

3. I have taken two hollow tubes of plastic (Polyurethane tube) and connected to Push fit connector as shown in the image.

1. Wrap any coloured tape of your choice on the ear tubes such that the wire and plastic get fit together.

2. Take Ear tips from any old ear phones or get it easily on shopping sites.

3. Connect the ear tips with ear tubes, make sure the diameter of both of them are same so that they can fit well.

Press the push fit connector to connect with tube of half a meter length.

The third image indicates the points where heart beat can be perfectly heard.

1. To make a chestpiece, take any plastic or medicine cup.

2. Make hole on the closed end such that the plastic tube can be easily inserted. The size of the hole should be perfect so that the tube fits well, the tube should be neither loose nor hard to insert.

3. Take a balloon and cut in half. Insert the bottom of cut balloon on the open end of cup.