Kids in preschool and kindergarten will love doing this hands-on oil and water experiment! It is an easy science experiment to set up and clean up, it smells great, and it yields colorful results. Learn about density and the basics of chemical bonds, plus have a ton of fun!
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Setting up the oil and water experiment was very easy. We gathered the following supplies:
- Clear baby oil
- Clear plastic or glass cup
- Several small cups
- Food coloring
- Plastic pipettes
- Printable science journal page (found below)
I poured about 1 cup of baby oil into a clear plastic cup and set it aside.
My kids filled the smaller cups with water and dripped a few drops of food coloring into each one. We ended up with cups full of purple, red, blue, and green water.
I printed out one science journal page for each child and we were ready to go!
Oil and Water Experiment
Before we dove into the experiment I asked the kids if oil and water mix. I explained to them that baby oil is similar to vegetable oil and motor oil. All oils are all made of nonpolar chemical bonds, regardless of their color. The kids recorded their thoughts on the science journal page.
Next, I showed the kids how to use a pipette to suck water up and squirt it out. They thought that was pretty neat!
Using the pipettes, the kids gently dripped colored water into the cup full of baby oil. They were surprised to watch the colored water fall in droplets through the oil all the way to the bottom of the cup. It was like watching colored rain!
The kids added all kinds of colors to their cups and even worked together to add four colors all at once. Watching the beaded water droplets fall to the bottom was hypnotic.
The Science Behind the Oil and Water Experiment
I explained that the reason oil and water don’t mix is because water is made of polar chemical bonds while oil is made of nonpolar chemical bonds. They’ll learn more about what that means in high school chemistry, but for now it’s enough for them to know that oil and water are simply held together by different kinds of chemical bonds that don’t mix together.
We also noticed that the water falls to the bottom of the cup. I asked the kids why they thought this happened and they immediately came up with the correct answer: Water is more dense that oil. Even if we put a lid on the cup and shook up the mixture, the oil would settle back on top with the water on the bottom.
They finished filling out their journal sheets and then asked to repeat this experiment. It was so fun and so colorful that we actually did it several more times!
Pro Tip: If you are like me and don’t have tons of money to spend on extra supplies, I discovered an awesome hack to reuse the baby oil. Once the kids are done experimenting, simply put the cup full of oil and water in the freezer. Within a couple of hours the water will freeze on the bottom and you can simply pour the baby oil right back into the original bottle to use again!
Be sure to download a free science journal page by clicking below. Have fun!