PH of Water – A Science Investigation Lesson for Years 5/6/7


Summary of Lesson Plan:

Students will be exploring what pH is and carrying out an investigation to find out whether all water sources have the same pH. Students will also find out the pH of safe drinking water. Prior to this investigation you will need to organise a range of local water samples that you have access to. You will also need to purchase a Liquid pH Test Kit. Each group will also need a small container/test tube to test water samples in and a teat pipette to add the pH indicator. I added the question: If we add liquids or powders to water does it affect the pH? Adding this allows students to explore some other colours on the pH scale rather than just the water spectrum of 6.5- 8.5.

Australian Curriculum Links:

Year 6 Science:

  • Biological Sciences:
    • The growth and survival of living things are affected by physical conditions of their environment.
  • Science as human endeavour:
    • Nature and development of science: Science involves testing predictions by gathering data and using evidence to develop explanations of events and phenomena.
    • Use and influence of Science: Scientific knowledge is used to solve problems and inform personal and community decisions.
  • Science Inquiry Skills:
    • Pose questions and make predictions about scientific investigations.
    • Construct and use a range of representations, including tables and graphs to represent and describe observations, patterns or relationships using data.
    • Compare data with predictions.
    • Communicate ideas, explanations and processes using scientific representations in a variety of ways.

Essential Questions:

  • Do all water sources have the same pH?
  • How does the pH of eater affect marine life?
  • What is PH and how do we test it?
  • What PH is safe drinking water?

Skills Taught:

  • Poses a range of Scientific questions.
  • Uses a range of scientific vocabulary.
  • Describe and predict the effect of environmental changes on living things.
  • Collect, organise and interpret data.
  • Communicate ideas.
  • Classify and organise diverse organisms based on observable differences.
  • Follow procedures to develop investigative questions.

Lesson Plan Sequence:

Introduction: 15 mins approx.

Focus: What do we know | what is pH?

  1. Discuss- what do we know about pH? What different water sources do we have access to? What is clean drinking water?
  2. Watch video: What is the pH scale
  3. More in-depth look at pH: pH Scale interactive notebook resource

Main Lesson: 50 mins approx.

Focus: Do all water sources have the same pH?

  1. Put students into small groups to carry out the investigation (3-4 per group)
  2. Explain investigation outline- read aloud


  • Create a hypothesis answering the investigation question in your Science book
  • Fill out the pH predictions for the different water sources (both pH number and whether acid or base)

Investigation Steps

  1. Use the syringe to get 10ml of water
  2. Squeeze the 10ml of water into your water test container
  3. Add 1 drop of the pH Dye Indicator using the teat pipette
  4. Place the lid on the water test container and lightly shake the solution
  5. Use the water pH colour chart to find the pH number it best matches
  6. Record the pH of the water source in the investigation table and write whether it is an acid or base
  7. Take a photo of the solution in the container using the iPad and put the photo on a book creator page (make the image small enough that you can fit all the pH solution images. DON’T forget to label the picture with the water source)

Closure: 10 mins approx.

Focus: Share findings

  • Discuss pH of safe drinking water (Article)
  • Students to record findings addressing hypothesis
  • Students to share what they found out about the pH of different water sources.

Follow Up Lesson Ideas:

  1. Graphing results: Students to create a graph on Excel showing the different pH levels of the water sources they tested.
  2. What is pH Activity: Students use the Scootle link to do an online pH experiment. Scootle Link.
  3. Aquarium pH: Explore the pH levels of aquariums activity. Students then research different aquarium animals and the pH level they need to survive.
  4. Aquarium Fish: Students choose an aquarium fish, find out the pH they survive in and design a fish tank.
  5. Math Project: Aquarium Volume: Students design and create a fish tank for their chosen fish/ sea creature. TPT link
  6. Global Education Lessons: The Safe Water Challenge. Students take an in-depth look at water and sanitation. Students explore countries that don’t have safe access to water. Global Education Lesson.


Download all of the lesson-related resources below:

External links to resources:

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