Quick jelly

Your neighbour is in a hurry to go to the shops but has to make a jelly. She asks you what is the quickest way to dissolve the jelly cubes in water. 

This session will take a total of 140 minutes, however, this time can be split into 2 lessons.

Equipment

• Eye protection may be needed depending on the methods chosen. It is always a sensible idea when liquids are being heated. 
• Heat source (Bunsen burner/hot tap/electric kettle/cooker/microwave)
• Containers (beaker/mixing bowl/pyrex dish/saucepan)
• Measurers (measuring cylinder/measuring jug)
• Stirrers (glass stirring rod/wooden spoon/fork)
• To make jelly pieces smaller (knife/scissors/cheese grater/potato masher/whisk/food processor).
• Thermometers
• Stop clocks
• Jelly moulds
• Jelly or a vegetarian alternative – 3 cubes
• Water

Health, safety and technical notes

• Read our standard health and safety guidance here.
• Wear eye and/or clothing protection if desired.
• This is an open-ended problem-solving activity, so the guidance given here is necessarily incomplete.
• Be aware of the safety aspects of eating jelly in laboratory, some student may react to certain ingredients. 

Possible approaches

This problem is open-ended. Many scientific points to consider, e.g. temperature of solution, particle size of jelly, rate of stirring. If this experiment could be done in the Home Economics department, students could actually eat their results (the experiment has cross-curricular possibilities).

Suggested write-up: student to write a note to a neighbour telling her how to make a “quick jelly”.

Possible extension

Ask students to “make the jelly solidify quickly”

How quickly can you get the jelly to dissolve without raising the temperature of the solution quickly? (Try and explain why this worked.)

FURTHER IDEAS:- Draw a plan of a machine that would make a jelly for a large party.

Notes

Try to make your experiment a fair test of your ideas.

The experiment must be repeatable.