cool density experiment

Top 20 Density Science Experiments

Welcome to our compilation of the top 20 density-related science experiments, specially curated for teachers and students.

Density, a fundamental concept in physics and chemistry, unveils the mysteries of why some objects float while others sink, and why certain liquids form layers instead of mixing.

These hands-on, enlightening experiments, suitable for learners across different age groups, promise to not only solidify your understanding of density but also kindle a burning passion for the intricacies of the physical world.

So, let’s plunge into the world of density-based science experiments!

1. Sink or Float?

In this experiment, students will explore the concept of density by investigating whether grapes, when placed in different concentrations of salt sh the power of centrwater, will float or sink.

Learn more: Salt and Water Density Experiment

2. Why Salt Water and Fresh Water Don’t Mix

By carefully pouring freshwater into a container of saltwater, students can observe the formation of distinct layers instead of immediate mixing.

3. Seven-Layer Density Column Experiment

Explore the fascinating world of density with the captivating “Seven-Layer Density Column Experiment.”

In this experiment, students will have the opportunity to create a mesmerizing column of liquids, each layer resting on top of the other based on its density.

4. Ocean Zone Jar

This captivating activity allows students to create a visually stunning representation of the ocean’s different zones.

5. Salt Volcano

Ignite your curiosity and unleash your inner scientist with the thrilling “Salt Volcano” experiment. In this exciting activity, students will create a volcanic eruption using just a few simple ingredients.

Learn more: Salt Volcano

6. Sugar Density Experiment

Indulge in the sweet world of science with the intriguing “Sugar Density Experiment.” In this experiment, students will explore the concept of density using various concentrations of sugar solutions.

7. Ocean Science

Dive into the fascinating world of ocean science with captivating activities specially designed for kids. From marine life to ocean currents, there’s a wealth of knowledge waiting to be discovered.

Learn more: Ocean Science for Kids

8. Underwater Color Explosions

Immerse yourself in a captivating underwater world with the mesmerizing “Underwater Color Explosions” experiment. In this visually stunning activity, students will explore the principles of density and chemical reactions by creating vibrant bursts of color in water.

9. Cork Sailboat

Set sail on a thrilling adventure with the “DIY Toy Sailboat” project. In this exciting hands-on activity, students can unleash their creativity and engineering skills by building their own toy sailboat.

10. Make a Water Strider

Experience the wonders of surface tension with the fascinating “DIY Water Strider” project. In this engaging activity, students can create their own water strider, a fascinating insect that glides effortlessly across the surface of water.

11. Build a Bottle Centrifuge

Unleash the power of the centrifugal force with the thrilling “Build a Bottle Centrifuge” project. In this hands-on experiment, students can create their very own centrifuge using simple materials found around the house.

12. Aluminum Foil Boat

Get ready to set sail on a buoyant adventure with the “Aluminum Foil Boat” project. In this captivating hands-on experiment, students can construct their own boat using just a sheet of aluminum foil.

13. Waves in Slow Motion

Experience the mesmerizing beauty of waves in slow motion with this captivating science experiment. By trying this experiment, students can observe and study the intricate movements of waves in a relaxed and detailed manner.

Learn more: Waves in Slow Motion

14. Lava Lamp

Ignite your creativity with the captivating “DIY Lava Lamp” experiment. In this mesmerizing activity, students can create their own mini lava lamp using simple household materials.

15. Floating and Sinking Soda Pop Cans

Dive into the intriguing world of buoyancy with the “Floating and Sinking Soda Pop Cans” experiment. In this exciting hands-on activity, students will explore the concept of density by investigating why some soda cans float while others sink in water.

Learn more: Floating and Sinking Soda Pop Cans

16. Burning Candle Density Experiment

Uncover the fascinating relationship between density and combustion with the “Burning Candle Density Experiment.” In this captivating science exploration, students can witness the impact of heat and combustion on the density of air.

17. Density Sensory Bottles

Engage your senses and explore the concept of density with the captivating “Density Sensory Bottles” experiment. This hands-on activity allows students to create their own sensory bottles filled with materials of different densities.

Learn more: Density Sensory Bottles

18. Floating Egg Science

Discover the wonders of buoyancy and density with the captivating “Floating Egg Science” experiment. This hands-on activity allows students to explore the principles of density and observe how it affects the floating or sinking of an egg in different liquids.

Learn more: Floating Egg Science

19. Raincloud in a Jar

Unlock the mysteries of density and cloud formation with the captivating “Rain Cloud in a Jar.” This experiment not only introduces the concept of density but also provides a practical demonstration of how clouds are formed in the atmosphere.

20. Exploring Density Marble Race

Embark on an exciting adventure of speed, motion, and density with the thrilling “Exploring Density Marble Race” experiment.

Learn more: Exploring Density Marble Race

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• Nov 18, 2019

10 Simple Experiments for Density and Buoyancy and Air Pressure

Updated: Jun 24, 2020

Develop an understanding of air pressure, buoyancy, and density using a series of hands-on labs.

When I’m teaching a science concepts like air pressure and density my goal is to help kids build mental models of what’s going on. Whenever possible I try to start with something they can touch and feel and experience. Here’s a simple sequence we did in my classroom. I hope you can see how students’ understanding builds.

1. Air is Stuff: Air Pressure Experiment with Water

This activity is a good place to start. When you try to pour water into the jug, it won’t go in. This is a concrete way to show that air is stuff. This always surprises and puzzles kids and encourages them to play. And when they’re intrigued, kids engage with difficult material more easily.

This is where we begin our study of buoyancy. Can you see where this will lead?

If you don’t get the idea that air is stuff, you won’t believe that it has weight. And if you don’t believe that air has weight, you won’t see how it can produce pressure. And if you don’t understand how air produces pressure, you won’t be able to see how it creates buoyancy. And if you don’t understand how buoyancy works, then it’s tough to grasp the concept of density. Sure, you can memorize the formula for density, but what does that tell you about density? BTW what IS the formula for density? And will it be on the test?

2. Matter Presses: Understanding Pressure

Once we proved to ourselves that air is stuff, we’ll play with the concepts of weight and pressure. This activity is free on my website. If you’re interested in a copy, you can sign up here.

This is a super simple activity to show kids how the weight of an object (our body) doesn’t change as you change your position (squatting, sitting, standing on tiptoe), yet its pressure does. It’s a concrete way for kids to feel the connection between the concepts of weight and pressure.

We’re just getting started on our investigation into density, buoyancy, and air pressure. These three concepts are related, and it’s helpful to study them together. In this activity, kids see how pressure comes from weight. We’ll continue that line of thought in the next couple of activities.

3. Streamlines: Water Pressure Experiments with a Water Bottle

Have you tried this experiment? It’s easy, a little messy, and super fun. Plus, kids find it intriguing, so that’s a huge point in its favor. 

How many observations can you make? Note how the lower streams are shooting farther than the upper ones. What could you conclude from that?

Click here (or on a pic) for middle school labs on this topic.

This is a visual example showing how pressure comes from weight. The greater push comes from the taller column of water. Kids can prove this to themselves by comparing bottles of different diameters and heights. It’s easy to conclude that it’s only the height of the water that changes the shape of the squirt.

This activity gives good evidence that the water sitting above the hole produces the pressure. This is a direct correlation to air pressure, which comes from the weight of Earth’s air sitting on top of you. 

The difficulty with understanding air pressure is that we ignore the surrounding air. We rarely think of air as sitting on us. It’s invisible so we forget it’s there.  Time to roll the tape from activity #1 . Air is stuff. It’s always there and we need to remember this to understand air pressure.

If you climb a mountain to a place where there’s less air above you, there’s less pressure. And vice versa, the lower you go, the higher the pressure. We call sea-level standard pressure, but if you go below sea level (into a cave for instance) air pressure increases. 

[Students may know that air high in the atmosphere is thinner than that near sea level. While that’s important, it’s a separate issue and we don’t deal with it yet.]

This is part 3 of our conceptual journey—we’ve determined that air is stuff and we’ve connected weight to pressure. The definition of stuff is that it has weight and takes up space. And if air has weight, it must be able to produce pressure by sitting on stuff. 

And what keeps air sitting on Earth? The same force that keeps every other substance sitting on Earth… gravity! Just because it’s light and thin and invisible doesn’t make it immune to gravity. Gravity gives air its weight and air’s weight produces pressure. It’s that simple. The complicated part is that we haven’t trained our brains to think in those terms. We forget that air is there and we forget that air is stuff. So it’s helpful to refer to experiments that kids have completed—like trying to pour water into a sealed bottle (experiment #1 ). The water won’t go in because the bottle is already full… of air.

And this is our job as teachers—to help kids think like scientists.

4. Nature Abhors a Vacuum: Playing with Suction Cups

Now that we’re beginning to get an idea of where air pressure comes from, what if we could change it? What if we could change the pressure around an object? How would that affect it? In this activity, we play with suction cups. Their shape allows them to trap some air and then change their volume. 

If their volume increases but the amount of air inside stays the same, the pressure will drop. Now the inside pressure is less than the outside pressure. It’s this small difference that makes suction cups stick. The higher outside air pressure is pushing them against the surface, keeping them attached.

This is a good activity to delve into the idea that pressure can come from two different sources. We’ve already looked at what causes the outside, or atmospheric, pressure (air’s weight). 

And now we’re looking at the pressure which comes from the air pushing against the sides of the container. All gasses exhibit this pushiness. This is a more common understanding of air pressure and one that confuses kids when they’re learning about atmospheric pressure.

5. Nature Abhors a Vacuum: Playing in the Tub

Who hasn’t tried this? Umm, a lot of kids apparently. Part of our job as science teachers is to help kids play with materials so they can discover concepts on their own. Play builds a library of phenomena and experiences that kids can refer to when unpacking their understandings.  Here they see how they can lift a full, upside-down cup and it doesn’t empty. It remains full until the rim of the cup breaks the surface of the water. They can use a bottle of any shape or size and see the same results.

What keeps the water in the cup? 

Water seeks its level by falling to the lowest point. But for water to leave this cup, a vacuum would have to form in the space since there’s no way for air to enter. The surrounding air pressure pushes on the surface of the water and holds the water in the cup. 

What if the cup were very tall, wouldn’t the pressure from the water in the cup overwhelm the atmospheric pressure? Yup!

Normal air pressure is about 15 pounds per square inch. For a one inch column of water to weigh 15 pounds, it would need to be about 32 feet high. 

Above 32 feet a vacuum would form and the water would not stay higher than that. This is the basis for early barometers. These were made with mercury because it’s super dense and therefore short enough to fit inside a room. Making a water barometer is a cool experiment if you have the time and space for it.

Do you see the barometer here? The sealed tube of mercury is inverted into an open dish of mercury, just like the experiment we did with the cup and water. As the room’s air pressure rises and falls because of changing weather, the height of the mercury will rise and fall.

(Click the image to go to the full painting)

6. Determining Density: An Experiment for Kids

This is the classic way to find the density of an object. While you can use anything that sinks, I prefer polymer clay. It’s sold under brand names Fimo and Sculpey, but there are off-brands too. The beauty of this clay is that it doesn’t dry out, doesn’t leave a residue, and you can use it in water. 

But why clay? By using clay, you can show that density is a quality of a substance. It doesn’t change if you have more or less of the substance. Kids can calculate the density for two or three different-sized lumps to prove this to themselves.

Click the image to go to the lab directions.

7. How do Boats Float? A Buoyancy Lab

You can understand floating and sinking in two ways: 

First, you can look at the way pressure changes with the depth or height of a fluid. As we saw in Activity #3 above, the pressure in a fluid depends on how deep the fluid is. The deeper you are, the higher the pressure is. So, if you’re standing in water, the pressure at your feet is higher than near your head. This difference in pressure causes a force that pushes you upward.

Do you float? It depends. You also have a downward force (your weight) so these two forces work against each other and the larger one wins. 

Another way to look at sinking and floating is to realize that water holds up the water above it. If you could remove a chunk of water and replace it with another object of identical size, will that object float or sink? It depends. If the object weighs more than the same volume of water, then it will sink. If it weighs less, it will float. And if it weighs exactly the same, it will neither float nor sink but stay where you put it.

It’s this second idea that we’re exploring here. We’re determining how much water an object displaces and whether that amount of water weighs more or less than the object. The cool thing about this procedure is that you can use it with floating objects. Here the boat displaces an amount of water. If we collect and weigh this water, we see that it weighs more than the entire boat. Here we're using polymer clay which is cool because it won't float if it's a solid ball, but it does float if its shaped like a boat. You could also use a square of foil to shape an aluminum foil boat but it's a little less forgiving when trying to reshape it multiple times..

So the weight of the boat (a downward force) is less than what the water can support (the upward force) and the boat floats. If we loaded the boat with weights, it would still displace the same amount of water. When would it sink? At the point when its weight increased beyond the weight of the displaced water. 

I like this setup because it’s simple and cheap to make and is easy to store.

8. Air Is Compressible: How to Deflate a Marshmallow

This activity uses two different pumps—one that pumps air into a bottle and one that pumps air out of a bottle. Can you think what beverage you might use each for?

I love using marshmallows for this since they’re soooo visual. This always draws a WOW from kids and they want to do it over and over. When you pump air in, the marshmallows contract and when you pump the air out, they expand. The marshmallows fatigue over time, but you can use them a few times for sure.

Here we’re back to exploring the idea that air pressure is a function of how much gas is inside a confined space. If you add more molecules to the space, the pressure goes up and if you take some out, the pressure drops. This doesn’t explain surrounding (ambient) air pressure or why that rises and falls, but it’s an important part of understanding.

9. Out with a Bang: Heat Causes Expansion

This is another not-to-be-missed activity that your students will want to try over and over. It’s simple and quick. I let them do it themselves, though I supervised closely.

Add a centimeter or two of water to an empty can. Place it on a hot plate until the water is at or near boiling. Using tongs, remove the can and invert it into a bowl of water. BANG! The can collapses instantly.

What’s going on? As you heat the water, it turns to gas and drives out much of the air that was filling the can. Since the water vapor is hot, it doesn’t take much to fill the can. When you place the can into the water, it cools and the water vapor condenses. The pressure in the can drops dramatically (since it’s sealed and no air can get in) and the higher outside air crushes the can.

Sometimes the can doesn’t get crushed, but fills with water. Can you see why? Here, the air pressure pushes water into the can until the air pressure inside and outside are equal. It’s the same explanation but with a different outcome. And if this happens, you can reuse the can for another try!

10. Local Pressure: Heat Causes Expansion

This is the last in our lineup. Here we add some very hot water to a milk jug and swirl it around to heat the plastic. Next we dump out the water and cap the jug and wait. Before long the jug implodes. It’s not as dramatic as the previous demo but it gets the point across. I appreciate doing different setups that focus on the same concepts. It helps solidify ideas.

Plus, we’re scientists, we repeat stuff.

As much as possible, we begin with concrete experiences that kids use to construct their understanding based on what they’re seeing. A sequence like this forms the basis of our comprehension and gives us something to discuss and return to again and again.

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21 Colorful and Creative Density Experiments for Kids!

August 29, 2023 //  by  Sharayah Lynn Grattan

To put it simply, how much of something can fit into a container or space? If we figure that out, we know the substance/object’s density! Many science concepts are hard to understand for kids, but density is excellent because it is very visual.

From liquid density experiments with food coloring to ping pong balls dropped in vegetable oil, we have all the whacky experiment ideas that will get your mini mad scientists jazzed about mass and volume.

1. What’s The Heavier Liquid?

To understand the concept of density in all of its forms, it helps to start with liquids we can easily differentiate. This fun experiment uses a glass of water, vegetable oil, food coloring, and salt.

Learn More: Buggy and Buddy

2. The Floating Orange

Here is a simple science experiment that teaches an important lesson about density. Grab 2 oranges, peel one and leave the skin on the other. Fill 2 glasses with water and put each orange in a cup. Watch your kid’s eyes get huge as they see the peeled orange sink and the unpeeled orange float!

Learn More: This Little Home of Mine

3. Burning Candle Density Experiment

Carbon dioxide has a higher density than air, so for this cool density experiment, you’ll want to have 3 candle sticks that are different lengths. Place them close together and light their wicks, then cover all 3 with a small glass container. Notice how the shortest candles go out first!

Learn More: Collection of Physics Experiments

4. Liquid Rainbow of Density!

For this density demonstration, you’ll have to prepare some liquids from your kitchen and bathroom. The liquids make distinct layers in the clear jar due to their different levels of density.

Learn More: Raising Dragons

5. Density-Inspired Sensory Bottles

Before you start this fun science experiment, explain the steps to your kids and help them come up with some questions and hypotheses about what they think will happen. Using 2 clear individual containers, fill one with water and one with corn syrup and leave some space for air, then add a few dense objects like buttons or rubber balls. How do the objects move in each liquid?

Learn More: The Educators’ Spin On It

6. Float or Sink?

The beginning of this experiment for kids starts with adding different liquids to a clear jar. Some you can try are honey, water with food color, and cooking oil. Then grab a variety of household items small enough to fit inside, and see where they settle in the layers of liquid density!

Learn More: Looking Out Loud

7. The Science of Grapes

Whether your kiddos like green or purple grapes, they will definitely LOVE this fun density experiment! We are testing to see if there is a difference in buoyancy in salt water versus tap water. Fill 2 glasses of these different water types and drop some grapes in. Which will sink and which will float?

Learn More: Rookie Parenting Science

8. Popcorn Mixing Magic!

To demonstrate how denser objects behave compared to lighter ones, we can do this exciting experiment using unpopped popcorn in a clear jar. For the light ball, you can use a ping pong ball, and the heavy ball should be metal for best results.

Learn More: Steve Sprangler

9. Can Eggs Float in Water?

You can teach your kids the science of density while preparing breakfast! Put water in 3 clear plastic containers and mix salt in one, sugar in another, and leave the 3rd alone. The 4th cup will have saline water. Grab 4 eggs and have your kids carefully drop an egg into each cup to see if they sink or float!

Learn More: Go Science Girls

10. The Density of Planets

The science of space for kids starts now! Out of all 8 planets, the least dense is Saturn. To explain this idea to your kids, the first step is to go outside and collect 7 small rocks together. Then your little artists can paint them to look like mini planets. To demonstrate, fill a kiddy tub with water, drop in your rocks, and watch them sink. For Saturn, use a foam or light ball that will float.

Learn More: Rainy Day Mum

11. The Beach in a Jar

Using our knowledge of density, we can create the layers of the beach inside a jar! From the sand to the sea floor, all the way up to the fluffy clouds. Check out the link to see how to assemble this simple density experiment.

Learn More: Lemon Lime Adventures

12. Sugar Rainbow Density

There are 6 colors in the rainbow, so put a teaspoon of sugar in 6 small cups. Grab your food coloring and add a few drops to the sugar then add water and stir. Using a syringe, add a little bit of liquid from each cup and watch how they make rainbow layers in the tube!

Learn More: Teach Beside Me

13. DIY Lava Lamps!

Did you know the far-out science behind lava lamps isn’t that hard to recreate? Using corn syrup, water, Alka Seltzer tablets, oil, and food coloring, you can help your kids make their own!

Learn More: Babble Dabble Do

14. Ocean Layers Experiment

There are 5 layers in the ocean and each has its own density. To create an ocean-themed density jar, you’ll add each liquid to the jar from most dense to least dense. Make sure each liquid has blue or some food coloring mixed in.

Learn More: Darcy and Brian

15. Racing with Marbles

For this exciting race, you’ll want to fill a few clear glasses with different liquids, some options are baby oil, corn syrup, honey, or shampoo! First, have your kids guess just by appearance which liquid they think is the densest. Then drop your marbles in and see in what order they sink!

Learn More: STEAM-Powered Family

16. Temperature and Density Experiment

Which is more dense, hot water or cold water? Well, turns out that because hot water molecules move faster this makes them less dense. So if you add different food coloring to hot water and cold water, pour the cold water into the jar first, then add hot water, the colors will stay separate!

Learn More: STEAMsational

17. Colorful Water Fireworks!

So the trick to this experiment is mixing the food color and oil together first, then pouring it into your warm water to create an awesome color show in a jar!

Learn More: Go Science Kids

18. Balloons of Density

Grab some balloons and get testing to help your kiddos better understand the 3 states of matter as well as their varying densities! Fill 3 balloons, 1 with air, 1 with water, and the 3rd with frozen water. Have your kids pick each balloon up and see which is the densest!

Learn More: 123 Homeschool 4 Me

19. USA Inspired Density Tower

Here is a density tower your kids can drink! There are a few different liquid options you can choose from that are blue and red to create your patriotic concoctions.

Learn More: Steve Spangler Science

20. Earth’s Atmosphere Density

Not only is this a lesson in density, but also your kids can learn more about the 5 layers of the Earth’s atmosphere and how they settled in the pattern they did.

Learn More: Line Upon Line Learning

21. Density in Clay

This fun and simple lab experiment is for kids a bit older that have access to measuring tools, clay, and a few small objects. Make sure their items are the same size and shape them and cover them in clay. Put them in water and see how their density will make some sink and others float.

Learn More: Engaging Science Labs

Seven-Layer Density Column

Anyone can stack blocks, boxes, or books, but only those with a steady hand and a little understanding of chemistry can stack liquids.

Print this Experiment

What if you could stack seven different liquids in seven different layers?

Experiment Videos

Here's What You'll Need

Light corn syrup, vegetable oil, dawn dish soap (blue), rubbing alcohol, lamp oil (select a cool color like red, available at a department store), glass cylinder, food coloring, food baster, seven plastic cups, scale (optional), let's try it.

Measure 8 ounces of each type of liquid into the seven plastic cups. Depending on the size of the glass cylinder, you might need more or less of each liquid—8 ounces is just a good starting point. You may want to color the corn syrup and the rubbing alcohol with a few drops of food coloring to create a more dramatic effect in your column. Here is the order of layers starting from the bottom and working your way to the top:

Honey Corn Syrup Dish Soap Water Vegetable oil Rubbing alcohol Lamp oil

Start your column by pouring the honey into the cylinder. It is very important to pour the liquids carefully into the center of the cylinder. Make sure the honey does not touch the sides of the cylinder while you are pouring. It’s important to let each layer settle before adding the next one. Take your time and pour slowly and carefully.

The next layer is corn syrup. Again, try not to let the corn syrup touch the sides of the container as you’re pouring. The key is to pour slowly and evenly.

Repeat the same procedure with the dish soap. Pour the soap directly into the middle of the layer of corn syrup . . . and take your time pouring!

Stop for just a second to enjoy your success. You’re almost halfway to your goal of stacking seven layers of liquid. The next liquid is water, and you’ll need to use the food baster—it’s like a giant medicine dropper for food. From this point forward, it’s okay to let the liquids touch the sides of the cylinder. In fact, it’s a must! Dip the tip of the food baster in the cup of water, squeeze the bulb, and draw up some water. Rest the tip of the food baster on the inside wall of the cylinder and slowly squeeze the bulb. Let the water slowly trickle down the glass to create the next layer. Take your time!

You’ll use the food baster once again for the next layer—vegetable oil. Use the inside wall of the cylinder to let the vegetable oil slowly trickle down and form the next layer.

Wash the food baster with some soap and water in the sink before moving on to the rubbing alcohol. If you have not already colored the rubbing alcohol, use a couple drops of food coloring to make sure this layer isn’t confused with water. Use the food baster and the inside wall of the cylinder to add this next layer.

You’re one layer away from success. Again, rinse the food baster in the sink before moving on to the lamp oil. Since lamp oil is flammable, you must do this last step away from any open flames. Use the food baster to draw up some lamp oil, which has a low surface tension and easily leaks out of the food baster. Keep your finger over the tip as you transport it over to the cylinder. By now you’re a pro at this. Use the baster and the inside wall of the cylinder to slowly add the final liquid layer.

Take your much-deserved bow and accolades from the guests in the viewing stands (or your friends hanging out in the kitchen). You’ve made a seven-layer science burrito, so to speak.

How Does It Work

The science secret here is density . Density is a measure of how much mass is contained in a given unit volume (density = mass divided by volume). If mass is a measure of how much “stuff” there is in an object or liquid, density is a measure of how tightly that “stuff” is packed together. Based on this density equation (Density = Mass ÷ Volume), if the weight (or mass) of something increases but the volume stays the same, the density has to go up. Likewise, if the mass decreases but the volume stays the same, the density has to go down. Lighter liquids (like water or rubbing alcohol) are less dense or have less “stuff” packed into them than heavier liquids (like honey or corn syrup). Every liquid has a density number associated with it. Water, for example, has a density of 1.0 g/cm 3 (grams per cubic centimeter—another way to say this is g/mL, which is grams per milliliter). Here are the densities of the liquids used in the column, as well as other common liquids:

The numbers in the table are based on data from manufacturers of each item. Densities may vary from brand to brand. You’ll notice that according to the number, rubbing alcohol should float on top of the lamp oil, but we know from our experiment that the lamp oil is the top layer. Chemically speaking, lamp oil is nothing more than refined kerosene with coloring and fragrance added. Does every brand of lamp oil exhibit the same characteristics? Sounds like the foundation of a great science fair project. So, the next time you’re enjoying a glass of iced tea, you’ll know why those ice cubes float. That’s right . . . it’s all about density.

Take It Further

If you want to create an even cooler science burrito, add the “meat and black olives.” In other words, select a few items from around the house (safety pin, key, staple, peanut, raisin, chocolate chip, small rubber bouncy ball, ping pong ball, etc.—be creative!) and carefully drop each item individually into the center of the cylinder. Some items will stay on or near the top of the stack of liquids and other items will sink part or all of the way down to the bottom of the cylinder. Why the difference? The densities and masses of the objects you drop into the liquids vary. If the layer of liquid is more dense than the object itself, the object stays on top of that liquid. If the layer of liquid is less dense than the object, the object sinks through that layer until it meets a liquid layer that is dense enough to hold it up. Here’s something else you can do to illustrate the connection between weight (or mass) and density. Set up a scale and weigh each of the liquids from your column. Make sure that you weigh equal portions of each liquid. You should find that the weights of the liquids correspond to their level in the column. For example, the honey will weigh more than the corn syrup. By weighing these liquids, you will find that density and weight are closely related.

Safety Information

Lamp oil is a flammable liquid and must be handled with care. Adult supervision is required. Need I remind you to never light your Seven-Layer Density Column on fire? Just don’t do it.

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Science Fun

Density Science Experiments

Easy density science experiments you can do at home! Click on the experiment image or the view experiment link below for each experiment on this page to see the materials needed and procedure. Have fun trying these experiments at home or use them for SCIENCE FAIR PROJECT IDEAS.

Liquid Sandwich:

Oil And Water Flip:

This Experiment Will Flip Your Opinion Of Density

Do Oil And Water Mix?:

Floating Water:

Why Does A Boat Float?:

Sugar Water Density Test:

Use Density To Make A Water Rainbow

Floating Grapes:

Can An Egg Float In The Ocean?:

Bubbling Blizzard:

Create A Beautiful Blizzard In A Bottle

Glowing Lava Lamp:

Rainbow In A Glass:

Buggy and Buddy

Meaningful Activities for Learning & Creating

April 10, 2016 By Chelsey

Exploring the Density of Liquids with Salt

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.

Follow our Science for Kids Pinterest board!

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
• Vegetable oil
• Food coloring

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.

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7 Colorful Density Experiments For Kids

What is density for kids? Density can be a hard concept for kids to get their heads around. But here we have a simple density definition and fun and hands-on density science experiments kids will love. Make a liquid density tower and explore the densities of liquids, investigate what happens to the density of water when you add salt or sugar, and more. Easy science project ideas for all ages of kids!

List Of Density Experiments

Below you will find great examples of density experiments. All of these science experiments are quick to set up and easy to do at home or in the classroom.

Get Your Free Printable Density Information Sheet!

Download this free density information sheet and our Best Science Practices mini pack to start your investigations with density!

Liquid Density Experiment

Explore how some liquids are denser than other liquids with this easy-to-set-up, 4-layer density tower experiment. Grab all the supplies you need from your kitchen cupboards. Get kids to predict which liquid they think will be more dense!

Floating Orange

Investigate whether an orange floats or sinks in water, and even add in the scientific method. Learn about buoyancy and density with a simple ingredient from the kitchen, an orange.

Halloween Density Experiment

Here is a spooky twist on our liquid density science experiment above. We even have a fun Valentine density experiment and a Christmas one too!

Lava Lamp Experiment

Compare the density of two liquids, oil and water in this homemade lava lamp. Add in a fun chemical reaction with Alka Selzter tablets, that will create lots of bubbling action.

Oil and Water

Look at this playful and colorful way for younger kids to explore oil and water , along with the concept of density.

Rainbow Water Experiment

Experiment with adding sugar to water to see if it increases the density of water. You will end up with colorful layers like a rainbow in a jar.

Salt Water Density

How does salt affect the density of water? Can you float an egg in salt water? Make up a salt water solution and find out!

Sink or Float Experiment

This is an easy-density experiment for younger kids and older ones, too! Why do some objects float and others sink? It’s all to do with density!

Skittles Experiment

Why don’t the dissolving skittles colors mix in water? Discover how differences in density slow down the mixing process. You can also set this up with M&M’s.

Density Defined For Kids

Density refers to the mass of a substance (the amount of matter in that substance) compared to its volume (how much space a substance takes up). Different liquids, solids, and gases will have different densities.

For example, a block of lead will weigh much more than an equal volume of wood, meaning the lead is denser than wood.

You can calculate density with this simple density formula.

Density = mass / volume

What Is Mass?

Mass is the amount of matter (consisting of atoms ) that make up a substance. What is the difference between mass and weight?

Weight depends on the force of gravity, so the weight of an object can change depending on where it’s measured. For example, a person’s weight will be much less on the moon, which has 1/6th the earth’s gravity.

Mass is a property of matter. The mass of an object does not change depending on where it is. Learn more about mass vs weight.

Density In Science

Density in science is an essential property because it affects how objects float or sink in water. For example, a piece of wood will float in water because it has a lower density than water. But a rock will sink in water because it has a higher density than water.

If you measure the mass of different liquids, the liquid with a greater mass for the same volume will be denser. If a liquid that is less dense than water is gently added to the water’s surface, it will float on the water. You can see this in our density tower experiment !

The Density Of Water

What is the density of water? The average density of water is calculated as 1 gram per milliliter (1 g/ml) or 1g/cm 3 .

Several factors affect the density of water, whether it’s freshwater or tap water, salt water, and the temperature of the water. Water is densest at 3.98°C and least dense at 0°C (freezing point). Adding things to water changes its density because those substances have their own density.

Several fun density experiments below explore some of these factors and how they affect water density.

Want to learn more about the density of the seawater in the ocean? Check out our layers of the ocean activity.

Turn It Into A Science Fair Project

Science projects are an excellent tool for older kiddos to show what they know about science! Plus, they can be used in all sorts of environments, including classrooms, homeschools, and groups.

Kids can take everything they have learned about using the scientific method , stating a hypothesis, choosing variables , and analyzing and presenting data.

Want to turn one of these density experiments into an awesome science fair project? Check out these helpful resources.

• Science Project Tips From A Teacher
• Science Fair Board Ideas
• Easy Science Fair Projects

More Fun Examples Of Density

Wouldn’t it be fun to stumble across a gold nugget in the ground, because even a small amount of gold is worth a lot! Gold weighs approximately 19 times more than the same amount of water. The density of gold is 19.3g/cm 3 .

LOOK: Parts of an Atom

In comparison, the density of Aluminium is 2.7g/cm 3 , which makes it a great metal to use for things that you want to be light. For example; cans, foils, kitchen utensils, window frames, and airplane parts.

More examples are copper – 8.92g/cm 3 , lead – 11.34g/cm 3 , and mercury – 13.53g/cm 3 .

More Helpful Science Resources

Here are a few resources to help you introduce science more effectively to your kiddos or students and feel confident when presenting materials. You’ll find helpful free printables throughout.

• Best Science Practices (as it relates to the scientific method)
• Science Vocabulary
• 8 Science Books for Kids
• What Is A Scientist
• Science Supplies List
• Science Tools for Kids

Printable Science Projects For Kids

If you’re looking to grab all of the printable science projects in one convenient place, plus exclusive worksheets, our Science Project Pack is what you need!

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~ projects to try now ~.

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Easy Density Experiments and Tricks for Kids

May 25, 2022 By Emma Vanstone 11 Comments

Density can be a tricky concept to grasp. Density refers to how much mass there is in a particular space. Imagine a drawer full of socks. It has a specific density. Suppose you take a sock out, the density of the drawer changes. This is because the mass of the socks has changed, but the volume of the drawer has stayed the same.

Generally, the greater the density of an object, the heavier it feels .

Solid substances are denser than their liquid and gas counterparts as the particles in a solid are much more closely packed together.

What is Density?

The density of an object is found by dividing the mass of the object by its volume.

Density Formula

Density = Mass divided by volume

The units used vary depending on the units of mass and volume used for the calculation.

If the mass is measured in kg and volume in cm³, the units for density would be in kg/cm³ .

Something else that can be confusing is mass. People often talk about weight when they mean mass and vice versa.

What is mass?

Mass is a measure of how much matter an object is made up of . The mass of an object remains constant unless you add to or remove part of it.

The weight of an object depends on gravity . Your weight would be less on the moon as there is less gravity, but your mass would stay the same.

You can do lots of very cool demonstrations to demonstrate density in a fun, hands-on way.  

Easy Density Demonstrations for Kids

These easy density demonstrations are super simple and brilliant fun ways to show kids ( and grown-ups) this tricky concept in action. There are also a couple of nifty tricks too!

How to make a Density Jar

Image taken from This IS Rocket Science

What you need to make a density column

Vegetable or sunflower oil

Food Colouring

Washing up liquid

Golden Syrup

LEGO or other small objects.

How to make a density column

First, make a very simple version using just oil and water.

• Pour some water carefully into a glass or jar.
• Very carefully add about the same volume of cooking oil on top.
• Carefully drop a couple of small objects into the mixture and observe what happens. Can you find an object to float on each layer?

What happens if you shake the jar? You should find that the oil and water mix up and then separate again.

To make a density column with more layers like the one above, you need lots of different liquids of different densities.

We used honey, golden syrup ( or corn syrup ), washing up liquid ( dish soap ), water and food colouring, and vegetable oil, in that order.

Density of Liquids

Each of the liquids has a different mass of molecules or different numbers of parts squashed into the same volume of liquid; this makes them have different densities. Therefore, one can sit on top of the other – the more dense a liquid is the heavier it is.

Objects and liquids float on liquids of a higher density and sink through liquids of lower density. The LEGO brick falls through the oil but floats on the water, while the coin sinks through both. The coin is therefore more dense than both the oil and the water. The plastic bug floating on the oil is less dense than both.

More Density Experiments

Homemade lava lamp.

Homemade Lava lamps are a fun activity demonstrating that oil and water don’t mix .

Density Trick using Salt and Water

Show your friends a science magic trick and a fantastic density demonstration . This activity uses salt to change the density of one colour of the water.

We also have a pirate themed density bottle. Pirate treasure is perfect for hiding in the layers.

Density and Floating Activities

Did you know that if you reduce the density of an object that sinks in water, it will float? We tried this with a heavy ball and used bubble wrap to make it less dense. The addition of the bubble wrap made the ball float!

You can also use the same logic to make a lemon sink or an egg float !

Science Concepts

More awesome science experiments for kids.

Don’t forget we have 100s more fun and exciting science experiments for kid s on Science Sparks.

Some of my favourites are our Fairy Tale Activities , where you can make a raft for the Billy Goats and a Zip Line for Jack and the Beanstalk. The infamous coke and mento explosion is always great fun to watch, and our water science experiments w ill keep you busy for weeks!

Wherever your interests lie, you’re sure to find something you like in our vast collection of science experiments and investigations.

Science Books from Science Sparks

I also have a couple of science books available you might like!

This IS Rocket Science

This Is Rocket Science includes 70 fun experiments for kids (and adults ) showing you how to use everyday items like bottles, cardboard, glue and tape to build excellent rocket ships, paper spinners and mobile rocket launch pads, all while learning about the scientific concepts behind space travel.

Snackable Science

Snackable Science  contains 60 edible experiments allowing kids to investigate their way around the kitchen, making magical mixtures, edible Jenga and Tetris, finding the perfect ketchup, and even creating their own super sour candy powder. It’s colourful, inviting and just brilliant fun.

Last Updated on January 29, 2024 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

September 07, 2012 at 7:38 pm

Oooooh! So that was it! *hunts for rainbow glass tutorial!*

September 08, 2012 at 12:05 am

Fun! We need to do this – I think my kids would love it!

September 08, 2012 at 1:38 am

Fabulous. I love the easy way you’ve explained it. Pinning to my science board 🙂

September 09, 2012 at 7:29 pm

Thank you. x

September 08, 2012 at 3:00 pm

I have treasures that would be great for this lesson.

September 09, 2012 at 7:28 pm

do let us know if you do it. x

September 09, 2012 at 8:25 am

Fantastic. Such a fascinating science experiment for kids!!! Love it.

September 10, 2012 at 6:29 pm

PS thanks for sharing on Kids Get Crafty!

September 14, 2012 at 10:26 pm

So cool!! I love it. Thank you for sharing on Sharing Saturday!!

April 21, 2013 at 8:55 pm

Another great demo for teaching density would be with pop. What you need is a fish tank full of water, a diet coke, and a regular coke. When you put the two cans in the water, the diet coke will float and the regular coke will sink. Explain to the kids that since the diet coke does not have as much mass, it is less dense so it floats.

August 03, 2021 at 7:58 am

Experiments like these are prefect for making learning fun for kids. It can spark their enthusiasm towards science. Thanks for sharing this idea!

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Science Experiments

Bottle Diver Science Experiment – A Scuba Diver in a Bottle

This experiment takes a few minutes to set up, but once done you can do the experiment over and over. Kids will enjoyed taking turns making the scuba diver move up and down in the bottle.

JUMP TO SECTION:   Instructions  |  Video Tutorial  |  How it Works

Supplies Needed

• Empty Plastic Two Liter Bottle
• Drinking Straw
• Small Paper Clip
• Play-dough or Reusable Adhesive Putty
• Thick Foil (I used a Foil Pan)

Bottle Diver Lab Kit – Only $5

Use our easy Bottle Diver Science Lab Kit to grab your students’ attention without the stress of planning!

It’s everything you need to  make science easy for teachers and fun for students  — using inexpensive materials you probably already have in your storage closet!

Bottle Diver Science Experiment Instructions

Step 1 – Cut out your diver using the same shape and size indicated above. I lightly sketched my diver on my foil before I cut him out. Note: That is a small paper clip. The diver should be approximated an inch and a half tall.

Helpful Tip: Download the Template for the Bottle Diver Here

Step 2 – Cut the straw and position it on the paper-clip as shown above.  Each end should be secured by the ends of the paper clip.

Step 3 – Slowly slide the straw onto the diver as shown above. The diver should look like he’s wearing a scuba tank. Then place a small piece of play-dough or putty on the diver’s feet.

Step 4  – Fill a glass with water and put the diver in. This is to test to make sure it floats. It should float as shown above. If it doesn’t float, your straw may have a hole in it. Try again with a new straw.

Step 5  – Fill the two-liter bottle with water. Make sure to fill it to the top, otherwise, the experiment won’t work.  Carefully place the diver into the bottle and screw on the lid.

Step 6  – What do you think will happen when you squeeze the bottle? What about when you stop squeezing the bottle. Write down your hypothesis (prediction) and try it out and observe what happens.

Do you know why then you squeeze the bottle the diver sinks to the bottom and when you stop squeezing the diver floats back to the top.

Find out the answer in the how does this experiment work section below.

Video Tutorial

Bottle Scuba Diver Science Experiment Step by Step Instructional Video

How Does the Science Experiment Work

This experiment is also referred to as the Cartesian Diver Experiment and it is a simple and fun way to teach kids about density and how it impacts whether an object will sink or float.

Density is a measure of the mass per unit volume of a substance. Water has a density of 1 g/mL (g/cm3). Objects will float in water if their density is less than 1 g/mL. Objects will sink in water if their density is greater than 1 g/mL.

When you first put the diver into the bottle, the combined density of the diver, straw, paperclip and playdough is slightly less than the density of water, so it floats. A small bubble of air gets trapped in the straw when you put the diver in the bottle. When you squeeze the bottle, you increase the pressure of the water in the bottle, so water is forced up into the straw compressing the air bubble in the straw. As the air bubble gets smaller, the density of the diver increases and the diver begins to sink. When you release the bottle, the pressure lessens and the water moves back out of the straw. The air bubble in the straw returns to its original size causing the diver to become less dense and float back to the top of the bottle.

Other Ideas to Try

Try this experiment in different ways – try it with cold water in the bottle and then try it with warm water in the bottle. Does temperature affect the density of the diver?

I hope you enjoyed the experiment. Here are some printable instructions:

Bottle Diver Science Experiment

• Thick Tin Foil (I used a Tin Foil Pan)

Instructions

• Cut out your diver using the same shape and size indicated above. I lightly sketched my diver on my foil before I cut him out. Note: That is a small paper clip. The diver should be approximated an inch and a half tall.
• Cut the straw and position it on the paper-clip as show above. Each end should be secured by the ends of the paper clip.
• Slowly slide the straw onto the diver as show above. The diver should look like he’s wearing a scuba tank.
• Place a small piece of play-dough or putty on the diver’s feet.
• Fill a glass with water and put the diver in. This is to test to make sure it floats. It should float as shown above. If it doesn’t float, you’re straw may have a hole in it. Try again with a new straw.
• Fill the two liter bottle with water. Make sure to fill it to the top, otherwise the experiment won’t work. Carefully place the diver into the bottle and screw on the lid
• Squeeze the bottle and watch as the diver sinks to the bottle. Stop squeezing and he will float back to the top.

Reader Interactions

February 15, 2016 at 2:45 pm

I’m looking for the pattern for the diver and I can’t find it on the website. Could you direct me to it or email it to me?

Thanks so much!

February 18, 2016 at 1:43 pm

Thanks for asking and for pointing out that it was difficult to find. Here is a link to download the template. I’ve also updated the instructions to make it easier to find.

Bottle Diver Template

Have fun with the experiment!

June 6, 2016 at 8:45 am

I’m having trouble getting the play dough to stick. Does blue tack or something else work better?

June 6, 2016 at 1:21 pm

I’d first try wetting the play dough just a little bit and then pressing it on the diver. That may do the trick. If not, blue tack should work or you could try silly putty.

Hope that helps!

March 10, 2017 at 2:23 am

HI Danielle! Actually i am looking for cool experiments about density.But in ur web all is like kids experiments.So can u give me suggestions some cool experiments with density?I am asking u because i have a competition to go through,so i really want to impress the judges.Please help me,Danielle

March 14, 2017 at 9:42 am

Here is a link to an list of simple experiments related to density. I hope it helps!

April 12, 2017 at 7:59 pm

I can’y get my scuba diver to go up it just sinks when I put it in!

October 24, 2017 at 9:42 pm

Maybe your scuba diver is too heavy, try removing some Play-Doh

July 5, 2022 at 1:30 pm

Will this work with liter bottles? I want to do this activity at the library and was hoping that all kids could take one home.

May 22, 2023 at 10:11 am

Great idea! It should. I definitely suggest testing first to make sure the results are what you expect prior to gathering materials for all the kids.

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Coffee Cups and Crayons

Simple play ideas, learning activities, kids crafts and party ideas, plus acts of kindness for kids!

July 10, 2014

Liquid Layers Density Science Experiment

Density can be a tricky science topic for kids to understand.  Making the concept hands-on with a density science experiment like liquid layers is a great way for kids to “see” density in action.

I’ve seen other people do this experiment before, but this was the first time I had ever done it myself.  Our first experiment didn’t turn out as well as I thought it would so follow the pouring directions below if you don’t have a lot of extra liquids when you try it!

Liquid Layers Density Experiment

• 100% pure maple syrup or corn syrup (or both)
• oil (we tried both olive and vegetable oil)
• rubbing alcohol
• food coloring (if you want to color the soap, water and alcohol)
• turkey baster, pipette, or medicine dropper

You pour the layers in one at a time starting with the maple syrup.  The first time we tried this we slowly poured them all into the center of our container and some of the layers mixed together–especially the soap and water!

This time we poured the syrup and soap in and then poured the water down the side of the jar.  We did the same with the oil and rubbing alcohol and ended up with some pretty colored liquid layers! Woo hoo!

How Does It Work?

The liquids all have different densities so they don’t mix together when layered from densest to lightest.

Join me and Erica from What Do We Do All Day? each Thursday this summer for a free Summer Science Camp .  We are sharing classic science experiments that your kids will love!

Head over to see the Homemade Compass they made this week!

Don’t let the fun and discovery stop there!

We have TONS of science experiments your kids will love on our  Super Cool Science Experiments for Kids  page! 

Take me to the experiments –>   Super Cool Science Experiments for Kids

About Megan Sheakoski

Megan is the creator of Coffee Cups and Crayons, a blog full of simple fun and learning. She believes that kids’ activities don’t have to be complicated to be fun and that learning is better with play.

July 10, 2014 at 5:00 pm

Great job – that can be a hard one! We’ve had success in the past by adding the layers, with a straw as a pipette, under each other, working from least to most dense last.

[…] Image Source/Tutorial: Coffee Cups And Crayons […]

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Density Experiment for Kids: Simple Density Tower

Science or magic? A fun density experiment for kids.

This density experiment is very neat. To kids, it appears more than a little magical but the effect is all science – no magic involved! The experiment involves forming a density tower using a combination of different liquids that form layers one atop another due to the differences in their density. Check the explanation below the experiment procedure for more about information about how and why it works.

Density Experiment for Kids: Density Tower

• Light corn syrup
• Concentrated dish soap – like Dawn
• Vodka or other alcoholic spirit
• Large jar or clear glass cylinder
• Food coloring (optional)

Hints & Tips:

• Supervise children carefully during this experiment. For children under the age of 12, it might be best for the adult to do the pouring. Use your best judgement.
• If you do not wish to use a form of alcoholic spirits, you can substitute rubbing alcohol. If you do this, the canola oil layer will go after the water layer, and the rubbing alcohol layer will be the final layer at the top of the density tower.

How to Build Your Density Tower:

1. Begin by pouring the light corn syrup into the bottom of the jar. The layer should be about an inch tall.

2. If you wish to color the light corn syrup, add a few drops of food coloring now, and stir with a fork or other object. We added a few drops of yellow food coloring to ours.

3. Next, pour the dish soap into the jar to layer on top of the oil.

For best results – each time you pour a new liquid into the jar, tip the jar to the side slightly and pour the liquid down the inside wall of the jar. Alternatively, use a turkey baster to put the liquid into the jar, again pouring the liquid down the inside wall. This will keep the pouring liquids from disturbing the liquids already in the density tower.

4. Mix a few drops of blue food coloring into some water and pour it into the jar. This will form your third layer.

5. Add a few drops of food coloring to your clear vodka or other alcoholic spirit. We used purple but you may want to use a different color if you want there to be a drastic difference between your layers. Pour the alcohol into the jar to create the fourth layer.

6. Top off the density tower with canola oil. You can color this with food coloring too if you wish.

7. Place a lid tightly on the jar, so that none of the contents will leak out.

8. Let kids have fun tipping the jar upside down and on its side, and then watch as the layers of the tower separate themselves once the jar has been placed face up again on a flat surface. Do not shake the jar, as this may cause some of the layers to combine.

How Do Density Towers Work?

An object’s density is calculated by dividing its mass (weight) by its volume (the amount of space it occupies). Liquids have density too. This experiment uses several different types of liquid to determine which is more dense. Lighter liquids are less dense than heavier liquids so they float on top of them.

For a density tower to work you also need to use the right types of liquids – those in neighbouring layers must be immiscible -that is, they do not mix. Learn more about this in our Oil and Water Experiment .

Christie Burnett is a teacher, author and mother of two. She created Childhood 101 as a place for teachers and parents to find engaging, high quality learning ideas.

Lava Lamp Experiment

Did you know that oil and water are not the same density? That is why oil and water don’t mix.

However, they will add up to something that’s more fun. This difference in density is the foundation of the fascinating Lava Lamp Science Experiment.

Combining elements of chemistry, art, and design, the homemade lava lamp offers science lessons about concepts of density, nonpolar liquids, and chemical reactions in an exciting and visually appealing way.

All you need for this engaging lava lamp science activity are simple household ingredients and a tall clear glass or bottle. This cool lava lamp science project is perfect for kids and adults alike.

Homemade Lava Lamp

How to make the perfect lava lamp? We experimented with a few different ways and will show you what we found out.

• oil (we used baby oil and vegetable oil)
• food coloring
• Alka-seltzer effervescent antacid tablets
• tall glass or bottle
• adult supervision

Instructions

• Fill the glass with 1 to 2 inches of water.
• Add your favorite food coloring.
• Fill the rest of the glass with oil but stop at about 1 inch from the top so that it won't bubble over.
• Drop an antacid tablet into the mixture and watch.
• Try using different sizes of alka-seltzer tablet.
• Try using different types of oil.
• Try mixing the different types of oil to get your favorite "lava" flow.

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Did you try this project?

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Density is the amount of matter in a given space, measuring how tightly packed the particles that make up a substance are.

Water is a polar liquid. It is slightly denser than oil, a nonpolar liquid.

Thus, if we mix the two, water will sink to the bottom while the oil will float above. This interaction forms the basis for the lava lamp science project.

The Reason Behind It

Alka Seltzer tablets contain three ingredients: aspirin (pain killer), sodium bicarbonate, and citric acid.

When immersed in water, sodium bicarbonate, and citric acid combine to produce sodium citrate, carbon dioxide, and water.

This sodium citrate can neutralize stomach acid. This is why alka-seltzer is an antacid medicine.

During the chemical reaction, carbon dioxide gas is created as a byproduct. Since carbon dioxide has a lower density than water, it forms bubbles that rise to the top, taking droplets of dyed water along with them.

These colorful bubbles create the energetic lava lamp display we associate with lava lamps.

When the bubbles burst , the blobs of colored water sink back to the bottom due to their higher density than oil.

The lava lamp action continues until all the ingredients in the tablet are used up.

Which oil is the best?

In our lava lamp experiment, we experimented with different types of oil to find the perfect lava lamp.

We first tried baby oil, which is clear, colorless, and has a pleasant scent. However, the bubbles produced were plenty and tiny, quickly clouding the solution and making it difficult to see the characteristic colorful blobs of lava lamps (the picture below is exceptional among many cloudy pictures).

The bubbles also fell quickly through the oil and back into the water. You could miss them easily if you blinked.

Next, we tried traditional vegetable oil, which worked much better.

The large bubbles of colored water fell gracefully through the vegetable oil, creating a better representation of the lava lamp.

However, the oil appeared yellowish, even though it was clear.

Preferring a colorless appearance, we attempted a third trial by mixing a small amount of vegetable oil with baby oil.

This combination resulted in slightly smaller bubbles than using vegetable oil alone, but they looked impressive and fell slowly and elegantly through the oil.

The oil mixture was also slightly yellowish but visually appealing, combining the best aspects of both oils. I think we have a winner!

It was combining the best of both worlds.

Note: There is no need for a dark background and backlight to create a spectacular lava lamp. The lava lamp project is splendid the way it is.

Through this simple lava lamp experiment, we observed the captivating interplay of liquid density, chemical reactions, and artistic design became a wonderful lava lamp science project.

Exploring Variations and Further Experimentation

To make your lava lamp science project even more engaging and educational, you can explore multiple variations and further experiment with different aspects of this. Here are a few ideas you can try:

1. Food Coloring: Experiment with different colors or combinations of food coloring to create a rainbow of lava lamps. Observe how different colors interact and how the hues change as the colored water droplets move through the oil.

2. Alka-Seltzer Tablet Sizes: Try breaking the Alka-Seltzer tablets into various sizes or using different quantities to see how the lava lamp action changes. Observe the differences in bubble size, speed, and duration of the lava lamp display.

3. Oil Types: As we discovered earlier, different oils can have varying effects on the lava lamp experiment. You can experiment further with other types of oils, such as coconut oil, canola oil, or even essential oils. You can witness how the lava lamp experiment behaves with these options.

4. Temperature Effects: Investigate how temperature affects the lava lamp action using hot water, cold water, or a combination. Analyze the impact of temperature on the density and behavior of the oil and water.

5. Bottle Shapes and Sizes: Try using different shapes and sizes of glass or plastic containers for the lava lamp science project. Observe how the container’s dimensions affect the movement and visual appearance of the colorful blobs.

So, gather your household supplies, and immerse yourself in the fascinating world of the homemade lava lamp.

Exploring various aspects of this experiment will not only give valuable science lessons.

This will also create a mesmerizing and colorful display that can captivate the attention of everyone around you. Enjoy the learning process and be mesmerized by the beauty of the lava lamp experiment as it unfolds before your eyes.

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