In this activity students devise and carry out experiments to test possible reasons for adding salt when cooking vegetables.
The Royal Society of Chemistry would like to thank the Discovery Channel for providing the video clips for this resource, and Twofour Productions for producing the clips.
If you teach primary science, see the headings below to find out how to use this resource:
Children will develop their working scientifically skills by:
- Selecting and planning the most appropriate ways to answer science questions, recognising and controlling variables where necessary, including:
- Carrying out comparative tests.
- 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.
- Observe that some materials change state when they are heated or cooled, and measure or research the temperature at which this happens in degrees Celsius.
- Observe that some materials will dissolve in liquid, forming a solution.
Children will learn:
- The temperature at which water boils.
- That irreversible chemical changes occur when food is cooked.
- That salt dissolves in water to form a solution.
Suggested activity use
The first activity will need to be carried out as a demonstration, or by children whilst being heavily supervised. This is due to boiling water being used.
The second activity can be carried out as a class investigation, with strong numeracy cross curricular links. Children may need support in the setting up of the investigation and with working out the dilution of solutions.
To carry out this activity you will require access to a cooker or hob to boil the water.
You should be very careful with boiling water around children, and a risk assessment and other health and safety considerations, such as those concerning food allergies, should be carried out.