Cornflour Slime

What you need

  • bowl
  • cornflour made from corn (not wheaten cornflour)—the amount will depend on how much slime you want. A 300 g packet of cornflour will make about two metric cups of slime.
  • food colouring
  • water
  • stirring spoon

What to do

  1. Put the cornflour in the bowl and while stirring, add water a little at a time until all the cornflour is wet. Add a few drops of food colouring to the mixture. Keep adding water and stirring until a thick slime forms.
  2. Make a fist and punch the surface of the slime—the slime will feel hard. Do the same thing, but very slowly and your hand will emerge from the bowl covered in wet, sloppy slime.
  3. If put in air-tight container in your fridge the slime should last up to two weeks.

What they learn

As your child plays with the slime they engage their sense of touch and help to expand their vocabulary when trying to explain how the slime feels.

Cornflour slime is a stir-thickening fluid, which means the more you stir it the thicker the slime becomes and when you stop stirring, it returns to its original state. Most fluids are ‘Newtonian’ and their thickness stays the same, whether or not they are being stirred.

Why does it work?

When cornflour slime is punched, the cornflour particles lock together and the slime feels like a solid. When the slime is moved more slowly, the cornflour particles have time to roll over each other and the mixture flows like a fluid.

Encouragement questions

  • What does the slime feel like?
  • What happens if you try to pick up some slime?
  • Is it runny like water or is it thick like honey?