What it shows
The heart beats faster when the body works harder. We can feel the pulse and count it to see the change.
The science
The heart pumps blood to every part of the body. Each beat pushes blood through the arteries, and we can feel it as a pulse at the wrist. When we exercise, muscles need more oxygen, so the heart beats faster to bring more blood. After resting, the heart slows down again.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A watch or clock with a second hand (free)
- Paper and pencil
- A friend or parent to help
- A clear space to jump
Safety
For this project: Do this only if you are well. An adult must watch. Stop at once if you feel dizzy or breathless. This is a learning activity and not a health check or medical advice.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
Step by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Sit quietly for two minutes.
Put two fingers on the inside of your wrist below the thumb to find your pulse.
Count the beats for 30 seconds while your friend watches the clock.
Write the number and double it to find beats per minute.
Do twenty jumping jacks or skips.
Count your pulse straight away for 30 seconds and write it down.
Rest for two minutes and count once more.
Make a bar chart of resting, after jumping and after rest.
What you should see
The pulse is highest straight after the jumps, and returns near its resting count after two minutes of rest.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
01What does the heart do?
It pumps blood around the body.
02Why is the pulse faster after jumping?
The muscles need more oxygen, so the heart works harder.
03Where can we feel the pulse?
At the wrist or on the neck.
04What brings the heart back to normal?
Rest.
Take it further
Compare your resting pulse with an adult’s and with a grandparent’s.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
Science projects
Easy Science Projects for Class 1 to 5
Simple, safe projects young children can make with a little help
Science projects
Biology Models Guide
Make the heart, lungs, kidney, eye, cell and more, and explain them well
Find out more about biology
Free, well-known places to explore the subject further. Ask a grown-up before you sign up for anything or type your name anywhere.