Our moving water science experiment was carried out by Tadhg, Cian and Sean.

We learned that when you heat up water, the water molecules start moving around faster and faster.   They bounce off each other and move farther apart. Because there’s more space between the molecules, a volume of hot water has fewer molecules in it and weighs a little bit less than the same volume of cold water.

So hot water is less dense than cold water.

When we put the two together with the hot water on the bottom, the hot water rose to the top, mixing with the cold water along the way and creating purple water.
When the cold water was put on the bottom, the hot water didn’t have to rise-it was already on top. The cold blue water stayed on the bottom and the hot red water stayed on top.