There are three different types of rocks: Sedimentary, Metamorphic and Igneous. This experiment uses sweets to demonstrate how the different types of rock are formed and what they look like.

You will need:

Aluminium foil

Starburst sweet x 9 (a range of colours is good)

Hot plate/similar


  • Unwrap 3 starburst and place them in a stack on top of a piece of foil. Wrap the foil around them so they are covered. Repeat this 3 times until you have 3 stacks wrapped in foil
  • Sedimentary rocks are formed by pressure over time. Take one of the stacks of sweets and squash them together – hard! You may even need to stand on them. The aim is to get them to stick together like a sedimentary rock!
  • Metamorphic rocks are formed by heat and pressure. Take another stack of sweets and place it on the hot plate until the sweets are soft but not completely melted. Adult supervision is needed for this. Remove from the heat and when they are cool enough to touch safely you can try squashing the sweets – they should squash much more easily and the colours will mix together more.
  • Igneous rocks are made with extreme heat (e.g. volcanoes). This time, place the last stack of starburst sweets onto the hot plate and leave it there until they completely melt into a liquid. Remove from the heat and allow the ‘rock’ to cool. Once it has cooled, open it up and you should find all the colours have completely mixed together and there are no clearly visible layers.
Why not check out the 3 types of rock science song to help kids remember what they have learned!

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