Water Science Experiments for Kids

I’ve lost count of the number of water science experiments we’ve done over the years. Water is pretty amazing. Did you know it is the only natural substance to exist in three physical states at temperatures naturally occurring on Earth?

Facts about Water

Water covers about 70% of the surface of the Earth.
Water expands when it freezes.
We need water to survive.
Water expands when it freezes.
Water can move upwards!!

Water has lots of properties that make it just brilliant for simple science investigations!

Water Science Experiments and Investigations

Freezing and Melting Investigations

Freezing and melting investigations are always fun. For younger children, let them play with ice cubes while they melt. You can freeze small toys inside to make this a bit more exciting.

We had great fun with our LEGO ice excavations recently, but you can also freeze superheroes, bugs or anything else that might spark an extra interest.

large block of ice in a black tray with lego bricks frozen inside. There are also syringes, droppers and a purple container on the table

Just getting the child to recognise that the ice is cold and how that feels on their fingers is a great sensory experience. Remember to let the ice melt a little first, as ice can be sticky when first removed from a freezer.

Frozen juice ice cubes used to make a slushy drink. A great experiment for learning about freezing, melting and other properties of water. #waterscience

Water Cycle Experiments

Make a mini water cycle or a water cycle in a bag. These are great science activities for older children and help explain a tricky concept.

Water and Density

Density is a tough concept to grasp, but hopefully, this density science trick is interesting and simple enough to help it all make sense. Salt increases the density of water, so the coloured salty water doesn’t mix with the less dense water on top!

Coloured water and salt density trick - cool science trick for kids

Density jars are also great fun. Children can try and find different small objects to float on the layers. These can be very simple and just contain water and oil, or children can experiment with layers of washing up liquid (dish soap ), treacle, honey and other non-toxic liquids.

Density jar -made of water with cooking oil floating on top. A coin sits on the bottom of the jar, a lego brick floats on top of the water and a plastic spider on top of the oil.

Transport of Water in Plants

Learn about transpiration and make some pretty coloured flowers. I love this activity. If it works well, you can see the path the water takes to reach the edge of the petals.

White carnation that has blue petals as it has been left in blue food colouring

Sinking and Floating Experiments

How about some simple sinking and floating experiments? This is great for young children, who love to watch objects sink and float. Older children can make a plasticine boat and discover whether an item that previously sank can float in the boat. Or, try and predict which objects will sink and which will float.

Did you know you can use a bit of clever density science to make an egg float?

Children can also make a lemon sink if they understand why it floats in the first place!

a large glass jar filled with water. A whole lemon is floating on top of the water and the inside of the lemon has sunk to the bottom.

Oil and Water Experiments

Find out why oil and water don’t mix. We’ve also demonstrated this using coloured water and pipettes, which was brilliant fun.

Coloured water and oil droplets suspended in water to demonstrate how oil and water do not mix.

Osmosis Experiments

Learn about osmosis ( water passing through a semi-permeable membrane ) using eggs. The term osmosis might sound complicated, but this egg demonstration makes it more understandable, and don’t worry if your children don’t understand straight away or are too young. It’s still fun to watch the eggs expand and then shrink.

Using eggs to explain osmosis. Two eggs in egg cups have no shell. One is full and swollen and the other small and shrunken

Absorbing Water

How about exploring absorption using sugar cubes? The fact that you can watch the water rise up the cube is brilliant and appeals to children of all ages.