You’ll need:
* Water
* Oil (any cooking oil will do)
* Food colouring (at least two colours)
* One tall glass (or jar)
* One small cup or bowl
* A fork
Instructions:
* Fill the glass almost to the top (around ¾ full) with room-temperature water.
* Pour about 2 tablespoons of oil into the small container. Add 2-3 drops of food colouring into the container, and whisk the two together using a fork. The food colouring will break into small drops.
* Slowly and gently pour the oil into the glass of water.
* Look at what happens, the food colouring will slowly sink in the glass, and then expand outwards as it falls. That makes the coloured parts look like they are dancing around… kind of like fireworks, right?
What’s happening?
Food colouring dissolves in water, but not oil. That’s why when you stir together the oil and colouring, they don’t really mix but form drops instead. When you pour the oil into the cup of water, the oil floats at the top because it is less dense than water. The food colouring drops, which were suspended in the oil, start to sink (they are also denser than oil) and then they dissolve into the water.
Photo credit: Carly Moniz/Wayland Free Public Library.
