What is density for kids? Density is one of the most important physical properties of matter and can be explored with simple hands-on activities. In these density experiments for kids, you’ll investigate why some objects float, why liquids form layers, how salt changes water density, and more. These easy density activities are perfect for introducing chemistry concepts at home or in the classroom.
👉 Looking for more chemistry activities? Explore our Kitchen Chemistry Experiments for Kids hub for simple investigations that teach chemistry concepts using everyday materials.
What Kids Learn About Density
Density helps explain why some objects float while others sink, why certain liquids form layers, and how changes in temperature or dissolved substances can affect matter.
Through hands-on experiments, kids can investigate how density influences the behavior of solids and liquids while building observation and critical-thinking skills.
Field: Chemistry—Physical Properties of Matter
Grades: 2–6
Concepts Explored: Density, mass, volume, buoyancy, floating and sinking, solutions, concentration, and physical properties of matter.
What Is Density?
Density describes how much matter is packed into a given space.
Different solids, liquids, and gases have different densities. Some substances contain more particles per unit volume than others, making them denser.
💡 A simple way to think about density is how much “stuff” is packed into a certain amount of space.
A material with a higher density contains more matter in the same volume than a material with a lower density.
Density affects many everyday observations, including:
- Why some objects float and others sink
- Why oil floats on water
- Why liquids form layers
- Why saltwater helps objects float more easily
You can calculate density with this simple formula:
Density = mass ÷ volume
Density Experiments For Kids
These hands-on density experiments make it easy to explore density with common household supplies.
Density With Liquids
Investigate how different liquids compare in density and discover why some liquids form separate layers.
Liquid Density Tower
Explore how some liquids are denser than others with this easy-to-set-up density tower experiment. Grab a few liquids from your kitchen and discover how they naturally form layers based on density.
Rainbow Density Column
Create a colorful rainbow in a jar while exploring how adding sugar affects water density.
Salt Water Density Experiment
Discover how adding salt changes the density of water and affects whether objects sink or float.
Hot And Cold Water Experiment
Explore how temperature affects water density and observe what happens when hot and cold water meet.
Floating And Sinking
Learn how density affects whether objects float, sink, or hover in water.
Floating Egg Experiment
Can you float an egg in salt water? Investigate how density and buoyancy work together in this classic science experiment.
Floating Orange Experiment
Does an orange float or sink? Test an orange with and without its peel to learn more about density and buoyancy.
Iceberg Density Experiment
Discover why ice floats on water and what happens when ice melts in freshwater and saltwater.
Lava Lamp Experiment
Compare the densities of oil and water while adding a fun chemical reaction that produces bubbling.
Oil And Water Experiment
Investigate why oil and water separate into layers and explore density with younger learners.
Skittles Experiment
Why don’t the colors mix right away? Learn how density can slow the movement of dissolved colors in water.
Density Defined For Kids
Density refers to the mass of a substance compared to its volume.
Mass is the amount of matter that makes up a substance, while volume is the amount of space that the substance occupies.
Because different substances contain different amounts of matter packed into the same volume, they have different densities.
For example, a block of lead weighs much more than the same-sized block of wood because lead is much denser.
What Is Mass?
Mass is the amount of matter that makes up a substance.
Weight depends on gravity and can change depending on where an object is measured. For example, an object would weigh less on the Moon than on Earth.
Mass, however, stays the same regardless of location because it is a property of matter.
👉 Learn more about matter here
Why Is Density Important?
Density helps explain many observations in everyday life.
- A piece of wood floats because it is less dense than water.
- A rock sinks because it is denser than water.
- Oil floats on water because it is less dense.
- Saltwater helps objects float more easily because dissolved salt increases the water’s density.
💡 Understanding density helps scientists study materials, oceans, weather, engineering, and much more.
The Density Of Water
The density of pure water is approximately 1 gram per milliliter (1 g/mL).
Several factors can affect the density of water, including:
- Temperature
- Dissolved substances such as salt or sugar
- Whether the water is fresh water or salt water
Water is most dense at about 4°C (39°F).
Many of the density experiments above explore how changes in these factors affect water density.
👉 Want to learn more about ocean density? Explore our Layers of the Ocean activity.
Think Like A Scientist
As you complete these density experiments, try asking questions such as:
- Which liquid is the most dense?
- Which object will float?
- How does salt affect water density?
- How does temperature change density?
- What patterns do you notice?
Record your observations and compare your results with your predictions.
Turn It Into A Science Fair Project
Density experiments make excellent science fair projects because there are many variables to test.
Try investigating:
- How much salt changes water density
- How temperature affects density
- Which liquids are most dense
- How different objects float or sink
- How sugar changes water density
Record your results in charts or graphs and look for patterns.
Fun Examples Of Density
Wouldn’t it be exciting to discover a gold nugget?
Gold has a density of about 19.3 g/cm³, making it one of the densest common materials.
For comparison:
- Aluminum: 2.7 g/cm³
- Copper: 8.92 g/cm³
- Lead: 11.34 g/cm³
- Mercury: 13.53 g/cm³
💡These differences in density help determine how materials are used in everyday life.
More Kitchen Chemistry Activities
Density FAQ
What is density in simple words?
Density describes how much matter is packed into a certain amount of space.
Why do some objects float and others sink?
Objects less dense than water tend to float, while objects more dense than water tend to sink.
What is the density formula?
Density = mass ÷ volume.
Why does saltwater increase density?
Dissolved salt adds particles to the water, making the water denser.
Is density chemistry or physics?
Density is a physical property of matter and is studied in both chemistry and physics.
What is a good density experiment for kids?
Density towers, floating eggs, rainbow density columns, and saltwater investigations are all excellent density experiments for kids.
Explore More Kitchen Chemistry
Continue the fun with our Kitchen Chemistry Pack featuring printable experiments, reusable investigation pages, science explanations, and easy hands-on activities using everyday kitchen supplies.
Perfect for home or classroom science with activities focused on:
reactions, mixtures, crystals, surface tension, polymers, and color-changing chemistry.
