Activity Introduction

Quick summary: This activity is designed to encourage children to investigate whether the objects sink or float in fresh water and saltwater. Children will discover that saltwater is denser than freshwater so objects float more easily in it, and they will observe that saltwater sinks when added to freshwater. Older children will also be introduced to a simple three-part structure for scientific inquiry: making predictions, observing results and thinking of possible explanations.  

This activity is designed to help connect children to the wonders of the natural world through sensory and play-based learning.

EYLF Learning Outcome


Outcome 1: Children have a strong sense of identity

2. Children develop their emerging autonomy, interdependence, resilience and sense of agency

Outcome 2: Children are connected with and contribute to their world

3. Children become socially responsible and show respect for the environment

Outcome 4 Children are involved and confident learners

1. Children develop dispositions for learning such as curiosity, cooperation, confidence, creativity, commitment, enthusiasm, persistence, imagination and reflexivity

2. Children develop a range of skills and processes such as problem solving, enquiry, experimentation, hypothesising, researching and investigating

3. Children resource their own learning through connecting with people, place, technologies, and natural and processed materials

Outcome 5: Children are effective communicators

1. Children interact verbally and non verbally with others for a range of purposes

3. Children express ideas and make meaning using a range of media

5. Children use information and communication technologies to access information, investigate ideas and represent their thinking


Resources required: 

  • Collection of jars or clear containers (you will need 2 jars per small group or pair)
  • Tap water
  • Table salt
  • Measuring cups
  • Large spoon for stirring salt into water
  • Food colouring
  • An eye-dropper
  • A variety of objects of a similar size but different weights. For example: a tennis ball and cricket ball; a ball and a balloon, a plastic block and a wooden block.
  • A range of floating objects. These could include: plastic balls, pencils, plastic bottle tops, old film canisters, paper clips, ice-cream sticks, leaves, twigs, string, small bars of soap, ping-pong balls or whatever other materials you have available.  

Supporting resources:


The team at Cool Australia continually reviews and refines our Early Learning resources in line with expert advice and current educational practices.


Teacher Worksheet

water-hero22-260x300Background information

Playing with salt water and fresh water is a great way to foster children's curiosity about why objects float and sink.

Children will experiment with different types of objects and vary the amount of salt added to fresh water in order to change the results of their experiment.

For older children, it is also an opportunity to learn about the basic structure of scientific inquiry: making predictions, observing results and thinking of possible explanations.

VIDEO: The Basics of Freshwater: Crash Course Kids (

Scientific Thinking:

This activity is designed to engage children in scientific thinking, wonder and exploration. Science is a way of thinking and understanding the world, interpreting experiences and collecting data. This will help children to form an appreciation and understanding of the world around them.

Children are naturally curious, and are intrinsically motivated to want to know and learn more. Duri

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