Sensory bottles aren’t just for small children- you can use them to explore the density of liquids in this fun science project for kids of any age. Observe what happens as you create your own sensory bottles and record your observations on our free printable.

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What are sensory bottles?

Sensory bottles (or discovery bottles) are simply empty bottles filled with various materials. They make a fun sensory play activity for babies, toddlers, and preschools and can even be used to encourage quiet time with children. They’re really mesmerizing to look at!

The Science of Sensory Bottles

We are taking a different twist with our sensory bottles and using them for a cool science project for kids! Children can explore the density of liquids as they create their very own sensory bottles. I’ve also included a free printable observation sheet for kids to record their findings. This post contains affiliate links.

Exploring Liquid Density with Sensory Bottles 

Materials for Sensory Bottle Science Experiment

• Clear bottle (We used empty, plastic Voss water bottles like these that we found at our local grocery store.)
• Water
• Oil (vegetable oil or baby oil)
• Food coloring
• Optional: Super glue
• Optional: Free printable recording sheet

Directions for Exploring Liquid Density with Sensory Bottles

1. Fill your bottle about halfway with water. Fill the other half with oil. What happens? Record your observation on the recording sheet.

2. Be sure your bottle is closed completely and gently shake it a couple of times. Observe what happens over the next few minutes. Record what you see.

3. Open your bottle and add a few drops of food coloring. What do you notice? Record your observations.

4. Gently shake the bottle a few times and record what you see.

5. What else could you add to your sensory bottle to observe? Try some of the ideas below (or your own idea) and record your observations on the recording sheet.

6. When you’re finished experimenting, have an adult seal your sensory bottle with super glue and use it for sensory play.

More Ways to Experiment with the Sensory Bottles

• What happens if you add the oil before the water? Do the layers settle in the same order as before?
• Try adding different liquids (like corn syrup) to the water and see what happens.
• What do you think will happen if you add some beads or glitter to your bottle. Try it and see!

What’s Happening?

Oil and water have different densities. Because the oil is less dense it rises above the water. When you add the food coloring, it only colors the water because it is a water-soluble dye.