filtration activity for kids

Filtration for children

So what is filtration?

It’s a process which is used to separate mixtures where small solid particles are suspended (floating) in either liquid or air. Filtration works because the filter has tiny holes, or pores, in which are large enough to let small molecules through, but not the much larger particles. The filtered liquid is known as the filtrate, while the particles that are removed are known as the residue.

There are filters everywhere, from the water jug in your kitchen that helps to remove water impurities, to filter papers for making coffee and even filters in our bodies. That’s right, our kidneys are a very important filter as they help to remove toxins from our blood.

Here’s a really simple activity for you to try at home, you’ll need a sieve, a colander, some flour, rice & pasta and a couple of bowls. It’s filtering, on a big scale!

You will need:

  • 3 bowls
  • spoon
  • ½ cup flour
  • ½ cup pasta
  • ½ cup of rice
  • Colander
  • Sieve


  • Mix flour, pasta, and rice together in a bowl.
  • The substances are all different shapes, sizes and weights- what would be an easy way to separate these mixtures?
  • Tip the mixture into a colander and shake the contents into a bowl. What happens?
  • Now tip the remaining mixture into a sieve and shake the contents over a bowl. What happens?
  • We’ve separated the 3 substances, rice, flour and pasta by filtration.

What’s the Science?

Filtration is a way we can separate a mixture, where the particles are different sizes, in this activity the flour and rice are small enough to pass through colander while the pasta is left behind. When we filter it again, using the sieve, this time the rice is too large to pass through so we end up with only flour remaining.

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