STEM projects at home

Science Skills at Home Series: Test, Improve, Blast Off!

I am here with a series of guides to show you how to improve your science skills without ever having to set foot in a lab! You don't need fancy equipment or special materials to become a scientist. We can investigate lots of things in our own homes.

Have you ever wondered how rockets manage to lift off the ground and travel through the air? You don't need a real launch pad to investigate the science behind rockets. With some simple household materials, you can make a safe model rocket and use the scientific method to find out what makes it travel further.

How Do Rockets Move?

A rocket moves because of thrust. When a rocket pushes gas or air backwards, the rocket is pushed forwards. This is an example of Newton's Third Law: for every action, there is an equal and opposite reaction. In your experiment, your aim is to provide enough thrust to beat the force of gravity, which pulls your rocket down to Earth.

You can investigate this principle without using fire, fuels or explosions. One simple experiment is a balloon rocket.

Your Mission

You will need:

• A balloon

• A long piece of string

• A drinking straw

• Tape

• Two points to attach the string, such as chairs

Thread the string through the straw and make sure it is pulled reasonably tight. Blow up the balloon, but don't tie it. Hold the opening closed and tape the balloon to the straw. When you're ready, let go!

The air rushes backwards out of the balloon, pushing it forwards along the string. Blast off!

Think Like a Scientist

The first test is only the beginning. Scientists don't usually get perfect results the first time. They ask questions, make predictions, carry out tests and use the results to improve their ideas.

This is called the scientific method.

1. Ask a Question

For example:

Does the amount of air in a balloon affect how far or how fast the rocket travels?

Do bigger balloons weigh more and need more thrust?

2. Make a Hypothesis

A hypothesis is a scientific way of describing your prediction. Write down what you think will happen before you test it.

Perhaps you predict that a balloon containing more air will produce more thrust and travel faster? Or that bigger balloons will weigh more and be harder to blast off?

3. Plan a Fair Test

A variable is anything in your test that can change, such as the amount of air, the balloon, or how high you hold it off the ground. Change one variable while keeping other important variables the same.

For example, you could test different amounts of air while using the same balloon, string and setup.

You could measure:

• How long the rocket takes to travel a set distance

• How far it travels

• How many times it completes the course in a fixed time

Repeat each test several times so that one unusual result doesn't affect your conclusion too much.

4. Record Your Results

Create a table of your measurements. You could then draw a graph to help you spot a pattern — a handy skill for GCSE Maths.

Don't worry if your results aren't exactly what you expected. Unexpected results can be some of the most interesting!

5. Evaluate and Improve

Now ask:

What could I change to make my experiment better?

Maybe the string wasn't completely straight. Perhaps the balloon was attached differently each time. Maybe measuring the time by hand made your results less accurate.

Scientists use their results to make improvements and then test again.

Your Engineering Challenge

Once you've completed your first investigation, design an improved balloon rocket.

Can you make it travel more quickly, or further?

Remember: don't just change lots of things at once. If you change one feature at a time, you can work out which change actually made a difference.

You could investigate the effect of:

• Balloon size

• Amount of air

• Rocket mass

• The shape or position of the balloon

• The angle of the launch setup

• Adding a nose cone to your balloon

The Big Idea

Making a model rocket isn't just about building something that goes fast. It's about asking questions and using evidence to find answers.

The scientific method gives us a cycle:

Question → Prediction → Test → Results → Conclusion → Improvement → Test again

That's how scientists and engineers solve problems in the real world. So if your first rocket doesn't perform brilliantly, don't give up. Use the evidence, make an improvement and launch again!