How to make a heart pump

Find out how the amazing muscles that make up your heart work to keep your blood pumping every day. Make a pump using a jar, a balloon, and two straws to get an idea of how your heart pumps blood.

Have your partner sit or stand still, so you can listen to their heartbeat. Place the stethoscope's sensor heard or one end of the cardboard tube on your partner's chest, slightly to the left. Place the earpieces in your ears. Or, if using a cardboard tube, put your ear up to the other end of the tube. Listen carefully. Do you hear a steady beat? Move the tube around until you can find the heartbeat.

Once you have found a steady heartbeat, set the stopwatch for one minute, and hand it to your partner. Start counting your partner's heartbeats as soon as your partner presses 'Start' on the stopwatch.

At the end of one minute, write down how many heartbeats you were able to count.

Have your partner repeat steps 1-3 while listening to your heart. Now, have your partner exercise for 15 minutes. Examples of this are: jogging around the house, jumping on a trampoline, and walking up and down the stairs. The key is not what your partner does, just that the activity is continuous for 15 minutes without stopping for a break.

After 15 minutes of exercising, measure your partner's heartbeat, counting how many beats there are during one minute. Write this new number down. Is it different from the number before?

Now it's your turn to exercise! Do the same activity that your partner did for 15 minutes without stopping for a break.

Once you've finished, have your partner count how many times your heart beats in one minute. Write the new number down.

What Happened: Exercise makes our heart beat faster. When our bodies are working harder, we need a steady blood supply. Our hearts provide blood to all parts of the body, even our brains! When we exercise, it also exercises the heart! Our hearts have to work a lot harder to pump blood while we are exercising. Our blood contains oxygen, which we need during exercise. As we use up the oxygen that our blood supplies, our heart has to keep pumping new blood into our system. Even after you were done exercising, your heartbeat was still faster than normal. This is because as your body cools down, you still need a strong oxygen supply. You can try the experiment again with less exercise (5 minutes) or more exercise (30 minutes). What are some times when your heart beat really fast? Why do you think that is? Sometimes something scary like riding a rollercoaster will make our hearts beat fast.