Kids love playing with water, especially when colours are involved!
This is a simple experiment to explain density (and no, it’s not the oil and water experiment!). You only need a few things that you probably have in your cupboard. There is a bit of cooling down time so keep that in mind before starting the experiment.
You will need:
– Sugar (1/2 cup, divided)
– Small pot
– 3 glasses or jars
– 2 food colouring (ideally primary colours, we used red and blue)
1. In the small pot, mix 1/4 cup of sugar with 1/4 cup of water. Whisk and bring to boil. Keep mixing until all the sugar is dissolved. Pour in one of the glasses and let cool down. This is your “medium density” liquid.
2. In the same pot, mix 1/4 cup of sugar with 30ml of water (that is half of a 1/4 cup). Whisk and bring to boil. Keep mixing until all sugar is dissolved. Pour in one of the glasses, add some red colorant and let cool down. This is your “high density” liquid.
3. In the third glass, add plain water and blue colorant. We used approximately 1/4-1/2 cup.
4. While you let the liquids cool down, you can do a “pre-experiment” to show that liquids with same density mix together. Using 2 others glasses with water, colour one in red and the other in blue. Mix them together. What happens? What colour is the water now?
5. Once the liquids have cooled down, let the kids see the difference between them. Which liquid moves slowly? Can you see through? Explain that the red liquid is more dense because there is more sugar inside.
6. Now it’s time to layer the colours and see if they will mix or not. Very carefully and slowly pour the medium density liquid (clear) over the high density one (red). What happens? Does it mix? Now carefully pour in the plain water (blue one, lower density). What can you see?
High density liquids are heavier so they stay on the bottom (or sink) and lower density are less heavy so they float. It’s the same concept when you try to mix water and oil. Water has a higher density than oil so it stays on the bottom (and those 2 don’t like to mix so you don’t have to pour them slowly!) you can also experiment with other object floating or sinking in water. For example, wood and plastic float (lower density) and metal objects sink (higher density).
If your kids love science, check out our Kids Fun Food Class, because nutrition is a pretty cool science!