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Heating and Cooling Activity for Kids

Rainbow Crayon DIY

  • Duration: 20-40 min
  • Difficulty: Medium
  • Cost: $0 to $5

Use heating and cooling to make a liquid rainbow from crayons!

Material List

  • 7Crayons with paper peeled off
  • 1Hair Dryer
  • 1Piece of paper
  • 1Cardstock (9 x 12)
  • 1Glue stick
  • 1Double sided piece of tape
  • 1Pair of safety goggles


  • 1Line up your crayons in the color order of a real rainbow.
  • 2Glue a piece of paper to the cardboard using a glue stick.
  • 3Attach the crayons to the top center of the paper using the tape.
  • 4Lean your cardboard at an angle against a few books.
  • 5Put on your safety goggles.
  • 6With the help of an adult, heat the tips of the crayons with the hairdryer.
  • 7Do not to touch the melted crayons until they have had time to cool.
  • Tip:Some hairdryers get hotter than others, make sure yours is a strong one.
  • Warning:This activity can be messy, be sure to protect the area you are working in.

How It Works

When you heated up the solid crayons, you caused the crayons to melt. The solid crayons became a liquid and dripped down the paper. As the liquid crayons cooled, they became a solid again. This activity is an example of a reversible change, since the melting was reversed once the crayons had a chance to cool.

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