This makes hot water less dense than room temperature water. Since hot water is less dense, it floats on the room temperature water. Fill one jar completely to the brim with ice water. Add two drops ...

How much depends on the jar that you’re using, but don’t worry, you can always add more if you need to. 2. Get a grown-up to help you add hot water to the jar and stir it with the spoon to ...

I have a few old clean tea towels around to sit hot jars on. And on a very hot day, a bucket of cold water for me to stand in! Step 1 - Wash thoroughly in hot soapy water, rinse and drain.