Density Experiments for Kids

Instructor: Shelby Golden
Get kids excited about learning about density with these experiments. These hands-on activities can help kids explore the scientific principles related to density while they have fun.

Orange Density

Use this experiment to help kids get a better understanding of density and how it can change. Here's what you'll need to conduct this experiment:

  • oranges
  • deep bowls
  • water

Fill a bowl with water for each group of children. They should then place their oranges in the water and see what happens. After noting that the oranges float, they should retrieve the fruit and peel it. Have your children or students place the peeled oranges back in the water to see if they get different results.

The peeled oranges should sink to the bottom of the bowl because their density has changed! Removing the rind, which was full of tiny pockets of air, means that the orange can no longer float in the water. Kids can learn more about this concept with this lesson on density.

What Floats?

Use this experiment to help kids learn about the density of various liquids. You can begin by collecting these supplies, increasing the amount depending on how many children are participating in the activity:

  • 1 c. of water (colored with food coloring)
  • 1 c. of light corn syrup
  • 1 c. of vegetable oil
  • nickels
  • grapes
  • Lego pieces
  • large clear containers

This experiment involves your students or children determining what objects will float in various liquids. Have them put grapes into individual containers with water, corn syrup and vegetable oil. Do any grapes float? Do any sink? Have the children record the results of this part of the experiment.

Repeat this process with the nickels and Lego pieces, recording the information after each step. Based on what they find, have your students or children discuss which liquid they think is the most or least dense and why. This lesson on predicting whether an object will float or sink can help students feel more confident in their knowledge of density.

Layering Liquids

You can use this experiment to build on what your students have been working on with density. It's a little messy, so make sure you're prepared before you get started. Luckily, it involves some of the same supplies as before. You'll need:

  • 1/2 c. of water
  • 1/2 c. of light corn syrup
  • 1/2 c. of vegetable oil
  • food coloring
  • large clear cups

Your students or children can apply the food coloring to the water to make it easier to see throughout this experiment. They should add the corn syrup into the bottom of their cup and then tilt the cup slightly, pouring the vegetable oil down the side of the cup. Have them record how the two liquids interact. Do they mix? Or do they stay separate?

You can ask them what they think will happen when they add the water. Once you've discussed the possibilities, the kids should add the colored water to the glass, taking care to pour it slowly down the side. Did the experiment go the way they thought? Have another discussion about the results of the experiment.

You can continue the activity by having your students or children mix the liquids together and then recording how they react. Do they stay together, or separate back out into layers? This activity works to demonstrate that liquids of different densities will not mix and will stay in distinct layers. This experiment gives students a visual representation of how density works.

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