Outreach: crystal chemistry


A fun experiment to grow your own crystals using everyday items

Grow your own crystals a simple demonstration using either Salt or Alum. The outreach activity was prepared for the Cambridge science festival 2014.


These resources were created for the Cambridge science festival 2014.

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

Skill development

Children will develop their working scientifically skills by:

  • Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.
  • Drawing conclusions and raising further questions that could be investigated, based on their data and observations.
  • Asking their own questions about scientific phenomena.

Learning outcomes

Children will:

  • Observe that some materials will dissolve in liquid to form a solution.
  • Demonstrate that dissolving, mixing and changes of state are reversible changes.

Concepts supported

Children will learn:

  • What happens in the process of dissolving, in simple terms.
  • That various factors can affect dissolving, and be able to provide examples.

Suggested activity use

This activity could be used as a whole-class investigation or as a guided group task to stimulate discussion and questioning. It provides a useful opportunity to demonstrate dissolving and that this is a reversible change. Also, it provides a chance for children to compare dissolving solids in hot and cold water and observe the differences. Children could try growing crystals from a range of solids to see which ones grow best.

Practical considerations

The time taken for the crystals to start to develop could vary from a couple of days to a week.

Health and safety considerations need to be taken into account, particularly with regards to children working with hot water.

Alum powder may be difficult to source for primary schools. Also, other simple equipment, such as several clean jam jars, will need to be sourced prior to the activity.