The aim of this topic is to simulate ways in which both extrusive and intrusive igneous rocks may form. A demonstration in which layers of sand and wax in a beaker of water are used to model how igneous rocks form both underground and at the surface.

If you teach primary science, see the headings below to find out how to use this resource:

Skill development

Children will develop their working scientifically skills by:

  • Researching using a wide range of secondary sources.
  • Drawing conclusions and raising further questions that could be investigated, based on their data and observations.
  • Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.

Learning outcomes

Children will:

  • Compare and group together different kind of rocks on the basis of their appearance and simple physical properties.
  • Observe that some materials change state when they are heated or cooled.

Concepts supported

Children will learn:

  • That rocks have different properties, often as a result of the type of rock they are and how they are formed. 
  • That rocks are natural materials whereas bricks are man-made (also referred to as manufactured).

Suggested activity use

This activity is best used as a demonstration to stimulate discussion around what children have observed and how this is a model for volcanic eruptions. This activity can lead on to subsequent activities where children research the formation of different rock types, in particular igneous rock. Children can also construct their own volcanoes and model eruptions using the reaction between an acid and a carbonate.

Practical considerations

Children will need prior knowledge of volcanoes and the structure of the Earth in order to fully appreciate and understand what the demonstration is modelling.

Specialist equipment such as Bunsen burners and glass beakers, or viable alternatives, will need to be sourced for this activity.

As with all demonstrations, a thorough risk assessment needs to be completed and other health and safety considerations need to be taken into account.

You should note that the curriculum links at the beginning of the document are now out of date.