This week we played with salt, ice and liquid watercolours. It was one of those cool activities that combines science and creativity, and has everyone happily engaged for hours.
What You Need
- One or more plastic containers – we used several, of different shapes and sizes. Ours had lids to make them easier to stack in the freezer.
- Water
- Salt
- Liquid watercolours or food colouring
- Plastic pipettes
- Tray or dish to stand your melting ice in
What We Did
I filled the containers with water and left them in the freezer for a couple of days.
We talked about the ways ice melts. The children said heat melts ice, so our ice would eventually melt if we left it out of the freezer. Or we could speed up the melting process by pouring on warm water. I asked them how we deal with icy paths in winter and they shouted “salt!”. We recalled how we added salt to ice to quickly freeze juice into a sorbet, and how that worked because the presence of an impurity (like salt) lowers the freezing point of water.
Then I handed over the salt and the liquid watercolours and let the children experiment.
They started out by sprinkling salt on the ice and noticing how the salt melted the ice where it came into contact with it. (Actually they started out by licking the ice – they do like to engage all their senses… I made sure this happened only the once, before any salt or paint had been introduced!)
Then C(9) had the idea of colouring her salt before sprinkling it on so she could follow its path. But she found the salt difficult to sprinkle when wet, so she decided to sprinkle and then quickly add colour. Soon she realised that she didn’t have to be so quick, because the colour always followed the path of the melting ice.
More colours were added…
And great fun was had by all!
I loved seeing how differently each child interacted with their ice. While C(9) enthused poetically about “glistening cataracts”, J(8) wore his best would-be world-dominating mad scientist expression as he attacked his with three purple pipettes at a time, shouting “I’m going to burn a hole RIGHT THROUGH THE HEART of it!”
Lots of creative expression, and some science too!
Variations
Using food colouring instead of liquid watercolour – I think I added too much water to our liquid watercolours – they were a bit wishy washy (not that the children noticed). While they were busy making cataracts and chasms, I privately experimented with using gel food colours instead. These highlighted the paths of the melting ice much more clearly, but one drop went a long way so the children wouldn’t have had nearly as much fun if we’d used these – their ice would quickly have been saturated with colour. The vibrant colours make for quite a cool demonstration, though.
Another scientific variation would be to experiment with different types of salt – rock salt, for example.
Further Resources
Our arty science project was inspired by The Artful Parent.
Ice Tunnels: Bring on the summer fun! I found this after we played with our ice.
I hope you enjoy playing with colourful salty ice as much as we did!
