Floating Rocks

Have your children seen stones floating on water? If not, you must show how a stone floats on water by conducting science experiments for kids. Do you know which stone floats on water? Pumice, a piece of rock, consists of gas bubbles giving a spongy appearance to them, allowing them to float. You can teach kids about floating rocks by showing them how a stone floats practically on the water. This helps them increase their observational and analytical skills. Most importantly, they can learn about the science behind floating stones. 


Once your children reach elementary school, you can introduce them to the concept of buoyancy which is the tendency of an object to float on water. This happens when there is a pressure difference in opposite directions of an object. The best example of buoyancy is floating rocks. You can also show how a piece of rock floats on water by conducting science experiments for toddlers, preschoolers and elementary school kids in the simplest way. This is one of the best DIY science project ideas for kids. 

Easy Science Projects: Floating Rocks

Do your children believe that some rocks float on water? If not, you can creatively show them how a rock floats on water. Kids can get hands-on experience in observing and learning about floating rocks through experiments. For this experiment, you can take different stones available in the surroundings or neighborhood. Besides this, allow kids to ask questions and come up with logical conclusions based on their observations. Performing science experiments enables children to expand their scientific knowledge for better learning outcomes. 

Floating Rocks

Aim of the Project 

The aim of the project is to perform the experiment on floating rocks using the stones or rocks available in the surroundings and record observations. 

Materials Required

  • Different kinds of stones or rocks, such as pumice, granite and pebbles. 
  • A clock 
  • A paper 
  • A pen 
  • A bowl of fresh water 
  • A bowl of saltwater 


  • Take different kinds of stones, such as pumice, granite and pebbles. 
  • Take a bowl of freshwater and label it as A. 
  • Take a bowl of saltwater and label it as B. 
  • Drop different types of stones on freshwater and saltwater bowls, respectively.  
  • Record the time with the help of a clock to check how long it takes for rocks to float or sink. 


In this experiment, kids observed that the pumice floats for more time in saltwater than freshwater compared to all other stones. The reason is that the pumice has pores that trap the air inside the water to float. The pumice floats for a longer period and then sinks in saltwater compared to fresh water because of its dense surface that allows the stones to float. The denser the water, the easier it is to float. If you soak pumice in water for a long time, the stone sinks in water immediately. 

Also, explore pepper and soap experiments

Benefits of Learning about Floating Rocks

The benefits of learning about floating rocks for kids are mentioned below. 

  • It increases the scientific knowledge of children while performing science experiments. 
  • It helps children learn the science behind the floating rocks with the help of experiments. 
  • It develops observational, analytical and critical thinking skills in children. 
  • It allows children to follow guidelines or instructions systematically for the successful completion of the experiment. 
  • It enables children to come up with logical conclusions for the experiments on floating rocks. 
  • It keeps children active and engaged while performing experiments. 

To know more information, explore science games for kids, STEM activities for kids in the kids learning section at Osmo.

Frequently Asked Questions on Floating Rocks

How to conduct floating rock experiments?

You can conduct floating rocks experiments by dropping some of the rocks, such as pumice, granite and pebbles, inside the bowl filled with saltwater and freshwater. Then, kids can observe that the pumice floats in saltwater rather than freshwater for a longer time compared to all other stones.

What are the benefits of learning about floating rocks?

The benefits of learning about floating rocks are that it helps children learn scientific concepts behind why some stone floats on water. Besides this, it enables children to develop observational, problem-solving, analytical and critical thinking skills while performing experiments on floating rocks.