Ice Balloons

Think Like A Scientist!

Einstein said, ‘The most beautiful thing we can experience is the mysterious. It is the source of all true art and science.’

This is an open ended exercise aimed at getting children to think like scientists rather than come to any conclusions.  However, it should act as a spark to ignite questions and set into motion further experiments.  And ice balloons are truly beautiful things!  We are absolutely indebted to the wonderful Exploratorium for this idea.


For this experiment you will need:

  • Some balloons (largely depending on the number of children, we would suggest a least one balloon for every three.  If you are doing this at home with just a couple of kids then it has to be a balloon each!)
  • Food coloring (red and blue works nicely!)
  • Paper clips, straightened out. (not those with colored plastic coatings!)
  • Wooden toothpicks
  • Flashlight
  • Hand lens/magnifying glass
  • A large bowl of water, small containers on trays to sit the ice balloons on.
  • Salt
  • Post-it Notes And Pens

What to do!

You will have to make ice balloons a couple of days in advance.  Fill your balloons with water until they are about ten centimetres in diameter.  Squeeze any excess air out of them before tying them and putting them in the freezer.  When frozen peel away the balloon and you will have your truly beautiful ice balloons.  Set them onto containers (rather like boiled eggs in an egg cup) so that children can explore their balloons.

At first get children just to look.  Make sure they have post-it notes and pens handy, get them to scribble down any observations or questions they have.  Darken the room if you can and hold a flashlight to the ice balloon.  Look closely using the hand lens.  Again encourage questions.

Use the wooden toothpicks and paper clips to poke the ice balloons.  What do children notice?  Do they have questions?  Write them down and save for later.

Now drop food coloring onto the balloons and observe.  What is happening?  Again this should give rise to questions!

Put the ice balloons into the large water bowl.  Do they sink or float?  If they float are they partially submerged? By how much?  Keep gathering questions.

Take the ice balloons out of the water.  Pour some salt onto the balloons, what happens?  Gather questions.

Stick all your post-it notes onto a board and save for later.  It is quite likely that children will want to play with their ice balloons until they are no more!  Let them explore for as long as possible.  They might want to use additional equipment for their exploration, if it is available and safe then why not let them go ahead?  You may be able to put the balloons back in the freezer to preserve them for experiments another day.  It depends on your scientists.

Later on, or the next day look at all the questions.  Get children to think about ways they might put their questions to the test.  The wooden toothpicks and paper clips might be a clue to thermal conductivity – what other materials could be used to test this?  What would happen if you used something other than salt? Why does the balloon float?  What floating tests can be carried out using water of different temperatures?

What has been learned?

Knowledge Base:

  • Children become familiar with properties of ice.

Scientific Enquiry:

  • Children learn to formulate scientific questions.
  • Children think creatively to suggest further experiments.

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