What children will learn
- Understand that liquids have different densities
- Make and test predictions
- Use the words 'dense', 'float' and 'sink' to explain results
You'll need
- A tall clear glass or jar
- Honey
- Dishwashing liquid
- Water with a few drops of food colouring
- Vegetable oil
- A spoon
- Small test objects: a grape, a cherry tomato, a plastic bead, a cork, a coin
Safety first
- Adult supervision required.
- Don't drink the liquids, and keep dishwashing liquid away from eyes — rinse with water if it splashes.
- Work on a tray to catch spills; oil and honey make floors slippery.
- Keep small objects away from toddlers, who could choke on them.
How to do it
- Pour honey into the glass until it is about a quarter full, pouring into the centre so it doesn't coat the sides.
- Slowly add a similar amount of dishwashing liquid, then the coloured water, pouring gently over the back of a spoon held against the inside of the glass.
- Finally, add the vegetable oil the same way. Watch the four layers settle — the densest liquid sits at the bottom.
- Before dropping in each test object, predict which layer it will stop in. Drop it in gently and record what happens.
- Talk about the results: why does an object sink through some layers but float on others?
Make it easier
Use just water and oil and watch them separate, then test two objects.
Make it harder
Weigh equal volumes of each liquid on kitchen scales to compare densities, and record the results in a table.
Parent tip: Leave the tower on the bench for a day and check whether the layers stay separate — it's a great follow-up conversation.
Fantastic work! Every little step helps you grow.