How to explain filtration to a child?

To explain filtration to a child, you can use the analogy of a sieve or a colander. Imagine you have a bowl of cereal with milk. If you pour it through a colander, the milk goes through the holes, but the cereal stays in the colander because the pieces are too big to fit through the holes. Filtration works just like that! It is a way to separate things that are mixed together. One part is small enough to go through a special screen or paper, and the other part is too big and gets stuck. We use this to make dirty water clean by trapping the dirt, or to make coffee by keeping the grounds out of your cup. You can also compare it to a playground slide where only kids of a certain size can go down, while others have to stay at the top. This simple visual helps children understand that filtration is about sorting things by size using a barrier with tiny holes.