If you add certain fresh fruit such as pineapple to jelly, it will not set. The task in this resource is to investigate why.
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 and fair tests.
- Using appropriate scientific language and ideas to explain, evaluate and communicate their findings.
- Drawing conclusions and raising further questions that could be investigated based on their data and observations.
- Compare and group materials together according to whether they are solids, liquids or gases.
- 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.
Children will learn:
- What happens when something dissolves.
- What happens when something changes state, and the variables that might affect this.
- That chemical reactions are often irreversible changes, with new products being formed.
- That jelly cubes dissolve in water, and don’t melt.
Suggested activity use
This activity could be used as a whole class investigation, with different groups of children investigating a variety of fruits determining whether they have an effect on how jelly sets.
It could also be used as a stimulus to look at other variables affecting how jellies set, or the rate at which jelly cubes dissolve. Variables could include the liquid being used, the colour of the jelly, the size of cubes used, whether stirring has an effect, the temperature of the liquid, etc.
A variety of different ingredients and equipment may be needed to carry out the activity, such as a range of fresh and tinned fruit, and a food processor. If you or the children decide to investigate the effect of temperature on dissolving then heat and/or cooling facilities will be needed.
To understand why different fruits affect the setting of jelly, a clear explanation of what enzymes are and how they work will need to be provided to the children.
Please be aware of any allergies to the fruits being investigated.