Geyser Science Experiment

Brace yourself for some blast-tastic science!

This sticky science experiment creates a fab fountain that looks just like a geyser – a natural spring of water that shoots out of the earth’s surface!

Geyser science experiment

Always do this experiment outdoors and ask an adult for permission before you start.

A clear plastic bottle with a yellow cap filled with liquid, a pair of red scissors, and six white round tablets are arranged on a white sheet of paper for a geyser science experiment.

What you’ll need…

A bottle of fizzy pop
Two pieces of A4 card
A tube of mints (Mentos work best)

Step 1

A person kneeling on grass holds a clear plastic bottle filled with liquid, unscrewing its yellow cap with one hand as they prepare for a geyser science experiment. The person is wearing blue shorts and a red shirt.

Go into the garden, put the bottle of pop on the ground and take off the lid. Make sure there’s lots of space around!

Step 2

A person in a red shirt prepares for a geyser science experiment by cutting a sheet of white paper with scissors on the left, then holding and folding the paper on a wooden table on the right.

Now, cut one of the pieces of card in half and roll it into a tube shape a little bit smaller than the neck of the bottle and secure with a small piece of tape.

Step 3

Split image: Left side shows a person cutting white paper with red scissors; right side shows hands pressing the cut paper onto the top of a plastic bottle filled with water outdoors for a geyser science experiment.

Next, cut a strip about 10cm wide and 15cm long and place it over the top of the bottle. Then, hold the cardboard tube on top, making sure it’s directly above the opening of the bottle.

Step 4

A person in a red shirt and blue pants sets up a geyser science experiment outdoors on grass, holding a rolled paper tube upright on top of a plastic bottle, with a square paper sheet wrapped around the tube.

Unwrap the mints and carefully drop them into the tube. Now, quickly pull out the at piece of card so that all the mints drop into the bottle/fizzy pop.

A bottle on grass shoots a tall, foamy white geyser upward in a classic geyser science experiment, with greenery and a stone wall visible in the background.

How does it work?

Fizzy drinks contain a gas called carbon dioxide that has been forced into the bottle under pressure – that’s why you hear that hissing sound when you open the bottle. The carbon dioxide makes bubbles and when the mints are added they start to dissolve and release gum arabic and gelatin into the liquid. These chemicals make the bubbles expand so quickly that the liquid is forced out of the top of the bottle, making a fountain!

Like our geyser science experiment? Let us know what you think by leaving a comment, below!