30 minutes

Students will measure out the length of a whale shark and compare it to lengths of other creatures in the ocean.


This lesson is intended to be used during the study of the book Jinormous Jack. It assumes the Lesson: Welcome back Jack has been completed.

You will need a large open space to complete this activity (your oval would likely be best).

You will also require:

  • a tape measure, trundle wheel or a number of metre long rules
  • some markers – witch’s hats, cones, bean bags or equivalent
  • sticky notes or masking tape to make note of what animal, each of your measurements represent.



Western Australian curriculum

Mathematics Measurement and geometry Using units of measurement ACMMG006, ACMMG019, ACMMG037



  1. Recall from your reading of Jinormous Jack, how big was Jack? (according to the story, you could hide a dump truck inside his mouth! Whale sharks are reported to grow to ~18 metres in length)
  2. How long is 18 metres? Would it be longer or shorter than e.g. a school bus? Is there anything in the ocean bigger than a whale shark? What about the other creatures in the story? Were they the same size as Jack?
  3. How many students head to toe would be the same length as a whale shark? How could we find out?
  4. Brainstorm a list of creatures that students would like to know about the size of (a list of some organisms and large objects and their reported lengths may be found below).
    • Blue whale – 33 metres
    • Whale shark – 18 metres
    • Humpback whale – 16 metres
    • Giant squid – 13 metres
    • School bus – 12.3 metres
    • Manta Ray – 9 metres (including tail)
    • Dugong – 4 metres
    • Bottlenose dolphin – 4 metres
    • Queensland groper – 2.7 metres
    • Grey reef shark – 2.6 metres
    • Potato cod – 2.0 metres
    • Bungarra lizard – 1.6 metres
    • Loggerhead turtle – 1.1 metres
    • Spangled emperor – 0.8 metres
  5. Take students onto the oval. Place a marker at your starting point and using your measuring device, measure 18 metres and place another marker. Identify your markers as the whale shark.
  6. Leave the whale shark measurement in place and measure out the length of the next creature students wished to know about.
  7. Continue until you have measured all of the creatures on your class brainstorm list. Discuss with students if the results were as they expected. Were some creatures smaller than they expected? Were others larger than they expected?
  8. Finish by determining how many students (head to toe) are required to be the same length as a whale shark?
Additional Resources

Barrymore, J. 2005, Jinormous Jack. Little Aussies, Fremantle, Western Australia.

Ganeri, A. & Jackson-Carter, S. (2014) Lifesize Ocean, Kingfisher, London.

Lesson: Discovering Ningaloo Reef

Lesson: What’s the difference – Year 1

Lesson: Welcome back Jack


jinormous jack, measuring, comparing lengths, whale shark size