Try this investigation to allow learners to explore the effect of heat on gases

This resource is also available in Welsh and Irish

This experiment focuses on gases and air pressure. First watch the video on how to carry out the ‘sticky cups’ demonstration, then find out how your learners can investigate how gases expand using water, a bottle and a balloon. 

Learning objectives

  • To understand that air is a fluid: it flows, can change shape and fills its container.
  • To learn that when air is warmed, the gases expand due to the increased heat.
  • To learn that particles in a gas move around and when heated, this movement is quicker and causes an expansion of the air inside its container.
  • To understand that when we consider the force of air over a specific area, we call this air pressure.

Enquiry skills:

  • Identify variables that can be changed, measured and controlled.
  • Record observations and explain what has been found.

Watch the video

The video below shows how to carry out the ‘sticky cups’ demonstration.

Source: Royal Society of Chemistry

Demonstrate the expansion and contraction of gases and make a pair of cups stick together.

Download the supporting materials

Set up and run the investigation with your class using the teacher notes and classroom slides, featuring a full equipment list, method, key words and definitions, questions for learners, FAQs and more.

Teacher notes

PDF | Editable Word document

Classroom slides

PDF | Editable PowerPoint document


What do learners need to know first?

Learners should understand the particle differences between solids, liquids, and gases. They should recognise that gases cannot be seen. They should be aware that air is made up of different gases and is all around us, and that gas particles move around freely.

Equipment list


  • 2 identical translucent plastic cups
  • Kettle
  • Kitchen roll
  • Plastic beaker

Individual investigation (each group will need):

  • Balloon
  • 500 ml plastic drink bottle
  • 2 bowls
  • Hot water (hot from tap, but not boiling)
  • Ice and water

Additional resources