Materials Needed for the Experiment:
- Vegetable, Canola, or any liquid cooking oil
- Cotton balls
- A clear container, such as a vase or tall glass jar
Make a Prediction
Before starting the actual experiment, gather some predictions from the students. Do they think a plain cotton ball will float in the water, or will it sink? If the children have experimented with these materials before, such as in the sinking and floating experiment, or the oil and water experiment, encourage them to use what they have already learned to make their predictions.
Begin by placing one or two plain cotton balls in the water. Cotton balls are interesting to observe because they float initially. When they become saturated with water, they sink to the bottom. Did the students predict this?
A Second Observation
Introduce the oil to the students by pouring a little into a small dish. Encourage the students to touch the oil and compare it to water using their sense of touch, sight, and smell. The students might use words like “slimy” or “slippery.”
Make Another Prediction
Ask the children for predictions about what will happen when the cotton ball is dipped into the oil and then placed in the water. Will it float, sink, or will it do something different?
Observe Again and Experiment Further
Looking for more experiments?
Curious minds always want to learn more! Here are some favorites:
- Sink or Float Experiment
- Discover magical fizzy fun with PTL’s Unicorn Fizz Experiment
- Baby Soda Bottle Experiment from PTL
- Fireworks in a Jar from ScienceSparks.com