Resources - Primary - Science

3rd September 2010 at 01:00

What the lesson is about

This is an experiment that demonstrates how gases take up more space than solids and liquids aimed at KS2 pupils.

Aims: pupils will -

- understand that some changes occur when materials that are not easily changed are mixed;

- make observations and record and explain changes using scientific knowledge and understanding.

Getting started

You will need film cases, Blu-Tack, water and effervescent tablets, such as vitamin C.

Demonstrate the gas rocket experiment to the class: half-fill an empty film canister with water, secure the tablet onto the lid with Blu-Tack, put it back on the canister and turn it upside-down. Retreat to a safe distance. The pressure in the canister will cause it to launch into the air. Ask the pupils what they can measure, such as how long the canister takes to launch, how high it goes, how long it stays in the air. How can they measure these? Suggest using video capture and stopwatches. Ask them what you could change, such as the amount of water in the canister or the size of the tablet.

Taking it further

Repeat the experiment and ask pupils to record their observations. What are bubbles? Drop a vitamin C tablet into water. How can we tell something is happening? Ask them to explain why the canister launches into the air. What does this say about the property of a gas? Crush a number of tablets and put them inside a balloon. Attach the balloon to the top of a bottle half-full of water so the tablets fall in and the balloon inflates, showing that gas needs more space than liquids.

Where to find it

The lesson, including instructions and list of equipment, was uploaded by Milk_no_ Sugar_Thanks and can be found at

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