20 February 2009

What’s it like – jelly?

Take a couple of packets of jelly.  Blackcurrant for preference (as that’s far and away my favourite flavour).


Marvel in the jewel-like colour and bouncy, chewy texture.  Marvel too in the taste if you’d like to!


Lose yourself in reverie temporarily as you dream of birthday parties and balloons and lashings of ginger beer…..

Oops – now snap back to the moment.

What’s it like – jelly?  A sticky, stretchy, translucent and sweet solid.

More to the point; what’s it for – jelly?

Well in the UK, we make our jelly using solid concentrated cubes like this.  We add hot water to melt the jelly so that it becomes a liquid, before ‘setting’ it in a cool place, turning it back from a liquid to a solid again.

Question.  Will jelly melt in as quickly in water that is not hot?  Let’s see.

You and your partner will need these things:

· one cup of cold water (let’s call her Katie Cold Water)

· one cup of hot water (Harry Hot Water)

· two jelly cubes

· two stirring spoons

· one stopwatch

This is a RACE Tommy.  A race between Katie Cold Water and Harry Hot Water.  To see who is able to melt the jelly soonest.

This is what to do.

· put one jelly cube into the hot water


· at the same time put one jelly cube into the cold water

katie cold

· stir each 20 times


· press the start button on the stopwatch

· as soon as a jelly cube dissolves press the lap button on the timer and record the time


So; what did we find out? 

  • That jelly melts fastest in hot water – to find out how fast, look at our results table where we have recorded the times. 
  • That a jelly cube dropped into cold water (poor old Katie Cold) had not even started to dissolve by the end of the school day.


We noticed some bubbles had attached themselves to the jelly cube.


And perhaps, if you look really closely, just the hint of a tinge of pink to the water.

katie cold

Sadly (!) a planned demonstration rather-too-close-to-the-school-for-comfort put paid to Friday’s observations, so we will have to wait until after the weekend to see whether poor old Katie Cold managed to ‘melt’ her jelly cube.

Do you think she will have managed it by then?

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