Water is one of the easiest materials for hands-on science. With cups, food coloring, paper towels, salt, ice, oil, and other common household supplies, children can explore capillary action, density, surface tension, freezing, pressure, polymers, refraction, and the water cycle.
Pick a Water Experiment
15 Water Science Experiments
Why Water Is So Useful for Science Experiments
Water is familiar, inexpensive, and visually easy to observe. More importantly, its unusual physical and chemical properties make it useful for demonstrating many scientific ideas. Water molecules are polar and attract one another, which contributes to cohesion and surface tension. Water also changes density with temperature, dissolves many substances, changes state between solid, liquid, and vapor, and interacts with light and other materials in ways children can observe directly.
If you want the science behind these activities before starting, see our Properties of Water: Physical, Chemical & Measurement Guide.
How to Turn an Activity Into a Real Experiment
The best part is not simply seeing a surprising result. Encourage children to use a basic scientific process:
- Ask a question. What do you think will happen?
- Make a prediction. Write it down before testing.
- Change one thing. For example, compare fresh water with saltwater.
- Observe and measure. Count drops, record time, compare water levels, or photograph changes.
- Explain the result. Was the prediction correct? What might you test next?
1. Walking Rainbow: See Capillary Action
You can't get enough colors, especially if it's a rainbow! But how about a walking rainbow? Well, you'll love to know how it works!
The Walking Rainbow experiment is simple and has a major wow factor. Children can watch the colored water stream, wipe with paper towels, and fill an empty glass.
The effect combines color mixing with capillary action. With paper towels (and plants work similarly), the water molecules attract the molecules in the paper towels. This causes the water to gradually move from the jar up through the paper towel and into the next jar. In the long run, the water level in every jar will level out. This is one of the most beautiful areas of Science!
2. Water Cycle in a Bottle
A straightforward water cycle science discovery container to explore earth science! It's certainly amusing to create fizzy blasts and eruptions, yet it's essential to explore our surroundings.
You cannot see each stage of the water cycle with this water cycle bottle, but it is a great hands-on project for discussing it with your children. It's a straightforward approach that provides children with a visual representation of the progression. Because it isn't a splendid, radiant day doesn't mean the water cycle isn't still happening.
Explore the water cycle in a bottle here.
3. Floating Egg: Explore Density
You need: two clear glasses, water, salt, a spoon, and two fresh eggs.
Fill both glasses with water. Stir several spoonfuls of salt into one glass until much of it dissolves. Gently place an egg into each glass and compare what happens.
What you should see: the egg in plain water tends to sink, while enough dissolved salt can make the egg float.
The science: dissolving salt increases the water's density. When the saltwater becomes sufficiently dense relative to the egg, buoyancy can support the egg.
4. Supercooled Water: Watch Ice Form Quickly
Under carefully controlled conditions, purified bottled water can sometimes be cooled below its normal freezing point while remaining liquid. Disturbing the bottle or pouring it onto ice can trigger rapid crystallization.
The molecules align methodically when water freezes, forming a crystalline structure. Along these lines, water molecules, such as those in ice, have less energy than water particles in a liquid state. The particles must lose heat energy as they change from liquid to solid water. As supercooled water freezes when you tap or open it, it also warms the remaining water.
5. Jumping Coin: Explore Expanding Air
Science experiments are enjoyable and an extraordinary means for kids to learn. Kids will appreciate watching a coin jump in this science activity and must repeat it multiple times.
At the start of the Magic Jumping Coin experiment, the air and the bottle are cold, a direct result of the cool water. The air warms up when you put your hands around the container's body, causing the air inside to expand thermally.
As the air molecules expand, they escape from the bottle or container in this manner, causing the cover, in this case, the coin, to vibrate or bounce around. This is the thing that makes your coin mysteriously jump! The coin will just quit jumping when the air inside the container inevitably cools off.
6. Why Does Water Rise in a Jar?
This is a magic-like experiment that will fascinate students. This is considered a standout among other science experiments. It demonstrates what happens to a fire when it runs out of oxygen and how a rapid change in temperature can create a vacuum or suction by adjusting the air pressure inside the jar.
Although we couldn't see it, the chemical composition of the air within the jar is changed by the consuming fire, and it requires time and air development to bring oxygen into the jar. It is a unique approach to demonstrate that although we can't see it, Science surrounds us.
7. Leak-Proof Bag: Explore Polymers
This activity doesn't take much time, and you're likely to have all the supplies around the house.
Turn on the water faucet and fill a sandwich bag or a Ziploc bag with water. Seal it up. Ensure the seal is closed securely. When you stick a sharp object through the water-filled pack, all the way through and out the opposite side, you'll surely get a leak.
But that's wrong! The laws of polymer science indicate that plastic sacks are made of long chains of atoms called polymers. This gives the pack elastic properties. The sharpened pencils slip between the atom strands without tearing the whole pack. Trust it or not, the long chains of molecules seal back around the pencil to avert leaks.
8. Water Fireworks: Explore Density and Mixing
Considering that you have a little one captivated by colors and fireworks, this basic test is for you (and your kid). You don't doubt trying this simple experiment, as all you need is already in your cupboard: oil, water, and food coloring!
This experiment is about density. Density describes how much mass is contained in a given volume.
Oil and water don't mix (because water molecules are more strongly attracted to each other than oil molecules). Oil is also less dense than water, allowing it to float on the surface and create two distinct layers.
9. Self-Inflating Balloon: Make Carbon Dioxide
If you have at any point been tasked with blowing up balloons before a birthday party, you've most likely longed that inflatables had a way of blowing themselves up. With this straightforward, simple science experiment, you can make that desire work out as expected.
The self-inflating balloon experiment is a genuine science activity ideal for science fairs or science lessons. In this lesson, kids realize that unusual chemical reactions and gases can be utilized to inflate balloons. The exact question is, will any inflatables have the capacity to float?
10. Pepper and Soap: Break the Surface Tension
You need: a shallow dish, water, ground pepper, dish soap, and a cotton swab or clean fingertip.
Pour a thin layer of water into the dish and sprinkle pepper across the surface. Touch the center with a tiny amount of dish soap.
What you should see: the pepper rapidly moves away from the soapy area.
The science: soap lowers the surface tension of water. The resulting difference in surface tension moves the surface water, carrying the pepper with it.
11. Lift an Ice Cube With String
You need: an ice cube, a glass of water, cotton string, and table salt.
Float the ice cube in water, lay the end of the string across the top, sprinkle a small amount of salt where the string touches the ice, and wait about a minute. Then gently lift the string.
The science: salt temporarily lowers the freezing point at the ice surface. As the diluted saltwater cools and refreezes around the string, the string can become attached to the ice.
12. Oobleck: Make a Non-Newtonian Fluid
Something is fascinating about sinking your hands into a bowl of superbly blended cornstarch and water.
This messy experiment is a memorable way to explore how some fluids behave differently under force. A blend of cornstarch and water demonstrates to kids the concept of non-Newtonian fluids while showing them generally accepted walking methods that prevent sinking. This well-known science activity features tags such as Oobleck and Cornstarch Quicksand. However, scientists refer to this substance, which behaves like both a solid and a liquid, as a non-Newtonian fluid.
13. Sink or Float Prediction Challenge
You need: a bowl of water and a selection of water-safe household objects such as a plastic cap, spoon, cork, coin, rubber eraser, or small toy.
Before placing each object in the water, predict whether it will sink or float. Record the prediction and result.
The science: floating depends on an object's overall density and the buoyant force from displaced water—not simply whether the object feels heavy or light.
14. Penny Drops: Test Surface Tension
All you need for this experiment is a couple of coins, an eyedropper or pipette, and water! How many drops fit on the surface of a penny? What else could you utilize? A bottle cap turned over, a flat LEGO piece, or another small, smooth, level surface! Guess how many drops it will take, then test it to see if you're correct.
Water's cohesion and surface tension become easy to see when the drops of water you add to the penny reach the penny's edge. Once the water has reached the edge, you start seeing a bubble or an arch framing the penny.
15. Make an Object Seem to Disappear: Explore Refraction
You can make glass objects disappear. Glass objects are noticeable because they reflect a portion of the light that sparkles on them and twist or refract the light that radiates through them. If you remove the reflection from and refract it by a glass object, you can influence that object to disappear.
Refraction occurs when light changes direction and speed as it travels from one medium to another. Just visible objects reflect light. When two materials with comparable reflective properties come into contact, light will pass through both at similar speeds, making the other material invisible.
What Children Can Learn From Water Experiments
Hands-on activities can help children practice observation, prediction, measurement, comparison, problem-solving, and explaining evidence. Water experiments are especially useful because one familiar material can introduce ideas from chemistry, physics, Earth science, biology, and environmental science.
For younger children, keep the emphasis on predicting and observing. Older students can record measurements, identify variables, repeat trials, graph results, and explain the mechanism behind what they observed.