Cracking Chemistry: National Science and Engineering Week


Cracking Chemistry is a selection of fun chemistry practicals developed by National Science & Engineering Week, curated by the Royal Society of Chemistry.

Cracking Chemistry is a selection of fun chemistry practicals developed by National Science & Engineering Week, curated by the Royal Society of Chemistry.


The British Science Association’s National Science & Engineering Week is a celebration of everything science, with grassroots events and activities across the UK every March.

This activity pack has been curated by Dr Suze Kundu for the Royal Society of Chemistry. It includes science investigations you can do to familiarise yourself with chemistry. These activities are an ideal way for schools, science clubs and even families to take part in chemistry hands-on activities and have fun.

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:

  • Asking their own questions about scientific phenomena.
  • Selecting and planning the most appropriate ways to answer science questions, recognising and controlling variables where necessary, including:
    • Carrying out comparative and fair tests.
    • Grouping and classifying things.
    • Finding things out using a wide range of secondary sources of information.
  • Drawing conclusions and raising further questions that could be investigated, based on their data and observations.
  • Using evidence from a range of sources to support and refute ideas.
  • Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.

Learning outcomes

Children will:

  • Compare and group materials together, according to whether they are solids, liquids or gases.
  • Observe that some materials change state when they are heated or cooled.
  • Identify the part played by evaporation and condensation in the water cycle and associate the rate of evaporation with temperature.
  • Know that some materials will dissolve in liquid to form a solution, and describe how to recover a substance from a solution.
  • Use knowledge of solids, liquids and gases to decide how mixtures might be separated, including through filtering, sieving and evaporating.
  • Demonstrate that dissolving, mixing and changes of state are reversible changes.
  • Explain that some changes result in the formation of new materials, and that this kind of change is not usually reversible.

Concepts supported

Children will learn:

  • That chromatography is a separation technique that can be used to separate different dissolved solids.
  • That some reactions are irreversible, in this case the chemical change of an Alka-Seltzer®.
  • That changes of state can occur when a substance is heated or cooled.

Suggested activity use

This resource provides excellent ideas for use in a science week or at a science club. Alternatively, there are individual activities that could be picked out to be used within specific topics of teaching, providing opportunities for whole-class discussions and observations, carrying out of fair tests and observing changes over time.

Practical considerations

Please take into account any health and safety considerations when carrying out these activities, particularly with the honeycomb activity and the preparation and use of borax. An adult will be needed to supervise this activity.

Chemicals required for the colourful combustion experiment and borax for the silly putty activity may be difficult for primary schools to obtain.