This week, as part of our learning about materials the class were set the challenge to find a way to separate 3 different materials (sand, salt and water) once mixed together to make a suspension.
Having learned about different ways to separate 2 materials (e.g. filtering, sieving, evaporating etc.) children decided to combine methods two methods.
They believed that filtering the mixture (pouring it through a funnel lined with filter paper) would first remove the sand and then the remaining salt solution could be left somewhere to allow the water to evaporate – leaving salt crystals. But were they right?
These two photos show the mixture immediately after being poured into the funnel and after four days. Can you see the salt crystals around the water line and at the bottom of the glass?