Today we are looking at filtering and how it can be used to clean dirty water.
What you need:
Dirty water ( or mud and clean water )
Coffee filter/paper towel/muslin
An empty bottle
Place your filter into the funnel and pour the water through slowly.
Is the water cleaner?
Can you see the solids trapped by the filter?
There are many different ways you could construct this investigation. You could try just one filter and talk about how it traps the big bits of mud and dirt but smaller particles pass through, or you could compare 2 or 3 different types of filters to see what happens.
Is kitchen roll better than a coffee filter, would just a sieve work?
You could also work in stages, so try a colander, then a sieve and then a paper towel. Each stage should trap smaller and smaller particles.
The Science Bit
A filter is a porous material which a liquid can be passed though to separate the liquid from solids suspended in it.
We also have this post where we filtered toys.