Activity Introduction

Quick summary: In this experiment students will learn about surface tension by creating conducting an experiment using cardboard fish, water and liquid soap.

These Snappy Science resources have been created to boost science education in primary schools across Australia. Each lesson is designed to support teachers with the scientific knowledge, ideas and resources to stimulate a sense of wonder and curiosity in their students. Many of the big issues that Australian society will face in the future are around technology, energy, resources and climate change. All of these require students to engage with science – but most of all to enjoy science!

Science at Home: These Snappy Science resources can also be used to engage families in fun science and learning for life. You can download a student friendly version of this activity here and you can also check out the Snappy Science Digital Library.

General capabilities: Critical and creative thinking.

Australian Curriculum content description: This activity is relevant to Science Inquiry Skills across all primary year levels of the Australian Curriculum.

Year 2 Science

  • Earth’s resources, including water, are used in a variety of ways (ACSSU032)

Year 5 Science

  • Solids, liquids and gases have different observable properties and behave in different ways (ACSSU077)

Syllabus OutcomesST1-9ES, ST2-7PW.

Time required: 10 – 15 minutes.

Resources required: Water, a bowl, liquid soap, cardboard, scissors.

Safety advice: Students may need assistance cutting the cardboard fish – depending on student age and ability this activity may be either a student-led experiment or a teacher-led demonstration.

Keywords: Fish, surface tension, liquid soap.

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian Curriculum.


Teacher Worksheet

Brief summary:

In this experiment students will learn about surface tension by creating conducting an experiment using cardboard fish, water and liquid soap.

Students can use the Predict, Observe, Explain table on the Student Worksheet to describe and reflect upon this experiment.

You will need:

  • Water
  • A bowl
  • Liquid soap
  • Cardboard
  • Scissors

What to do:

Step 1. Cut out little fish shapes from the cardboard.

Step 2. Fill the bowl with water.

Step 3. Carefully float the cardboard fish on the top of the water.

Step 4. Add a drop of liquid dish soap behind the fish’s tail. What happens? The fish swims away!

How does it work?

Surface tension basically means that there is a sort of skin on the surface of water where the water molecules hold on tight together. If the conditions are right, they can hold tight enough to support your fish. The fish is not truly floating, it is being held up by the surface tension.

Adding the liquid soap breaks the water's surface tension, a

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Student Worksheet

In this activity you will experiment with surface tension.


Explain what you think will happen:


Explain what happened:


Explain why you think this happened:

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