This simple science demonstration is a fantastic way to learn about density! Liquids can be stacked in a glass or jar in order of their density. As an additional challenge, children can experiment with small items to determine which floats on each layer.
Christmas Density Jar
You'll need
Sugar Syrup
Water
Food colouring
Vegetable Oil
Small items to test for floating
Other things to try:
- Honey
- Treacle
- Washing soap
How to make a Christmas Density Jar
Pour each liquid into the glass slowly, starting with the sugar syrup (you can add food colouring if you like), followed by the water with added food colouring, and finally, the vegetable oil.
Drop a few small items in and see which layer they float on.
Try a marble or a coin to see if it sinks to the bottom.
Why does this work?
Each liquid has a different mass of molecules or different number of parts squashed into the same volume. This means they have different densities, allowing one to sit on top of the other. The denser a liquid is, the heavier it is.
Objects and liquids float on liquids of a higher density and sink through liquids of lower density.
We’d love to see your Christmas themed density jars.
If you like this activity, don't forget to check out my other Christmas science ideas.
Last Updated on December 17, 2025 by Emma Vanstone
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