This modified version of a lava lamp is definitely one of our favorite cool science experiments! It’s a super fun way for kids to explore the density of liquids using materials you have right in your kitchen.
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We have a lot of cool science experiments for kids on Buggy and Buddy like this Baggie Burst experiment and exploring Colorful Chemical Reactions! I think this exploration of liquid density ranks right up there with our favorites!
With just a few household materials, children can explore the density of liquids and even practice mixing colors in a super fun way! (This post contains affiliate links.)
See it in action here!
Cool Science Experiments: Density of Liquids
Materials for Science Experiment
- Clear glass
- Water
- Vegetable oil
- Food coloring
- Salt
Science Experiment Procedure
1. Fill your clear glass about 2/3 of the way with water.
2. Pour vegetable oil into your cup. (You want to create a layer that’s about 3/4-1 inch high.) What happens to the oil after you pour it in your cup? Why do you think this happens?
3. Add one drop of food coloring to the cup. What happens to the drop of food coloring? Why do you think this happens?
4. Sprinkle salt into your cup and watch what happens!
5. Continue adding more salt and observe. (The kids started by doing small sprinkles of salt, then progressed to adding big pinches of salt, and then spoonfuls of salt.)
6. Allow time for your child to explore the setup on their own. Lucy (6 years old) wanted to add different colors of food coloring to her cup to see what would happen.
This science activity was a great sensory experiment for Theo, my 3 year old. He loved watching all the movement in the cup and would even stick his finger in the liquids to see what would happen!
What’s Going On?
In the beginning of the experiment, the oil settles above the water because it is less dense. When you add salt to the to the cup, the salt sinks to the bottom of the cup since it is heavier than the other two liquids. The salt carries a blob of oil with it. As the salt begins to dissolve in the water, it releases the oil which floats back up to the top.
Be sure to try this similar density experiment– comes with a free printable too!
Want to go even further?
Even more activities to inspire creativity and critical thinking for various ages.
1. Try this Dancing Raisins experiment. How is it similar to the one you just did? How is it different?
2. Explore the density of objects in this simple sink and float experiment.
3. Try this Seven Layer Density Column experiment.
