Make sure you follow my STEM board on Pinterest for more ideas, and don’t forget to save the pin for later.

Phew! Last week was a scorcher of a week. I thought I had missed all the really hot weather when I was on holiday, but apparently not. I am the first to admit that I don’t do well in temperatures that go above 22c, I much prefer the cooler weather. So last weeks activity came at just the right time.

You will need:

  • 2 zip lock bags
  • Tape (optional)
  • Ice
  • Salt
  • A drink

This is a really simple science experiment, which has the added bonus of being edible.

Simple pour a drink into the first zip lock bag and seal tightly. I sealed it shut with some duck tape just to be sure.

Place that bag into another zip lock bag and fill with a couple of handfuls of ice.

Next add some salt, you will need quite a bit of it.

Then seal the bag and shake it for about 3-5 minutes. You should find that the drink inside the first bag begins to turn into a slushy.

My top tip is to either do this over a sink, or wrap it up in a towel to stop any salty water from escaping.

When you are happy with the consistency, open up the inside bag and pour it into a glass to enjoy.

It certainly was a welcome relief as an afternoon refreshment.

The Science Behind It

When you add salt to the ice it lowers the freezing point, making the mixture cooler than just ice by itself. This colder temperature is enough to start freezing the drink that you have added. If you leave it long enough you should be able to freeze it sold.

Pin for later:

Make a cooling slushy in a bag using ice and salt. It makes a fun and edible stem activity on a hot day.