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Biological Timescale

The Earth has existed for 4.5 billion years. That is an incredible length of time for students and adults to comprehend. In this activity, students imagine that time can be squished, and will construct a simple timeline of life using a 100 metre tape. Students will gain an understanding of the immenseness of our planet’s history and the brief period dominated by dinosaurs and then humans.


  • Explain the biological timescale using a model.


  • 100 metre measuring tape (as used in track and field sports)

  • flagging tape

  • marker

  • masking tape

Key Questions

  • What type of organism has been on Earth the longest?
  • The dinosaurs died out about 65 million years ago. How many more years was it until the first human ancestor appeared?
  • What type of animals were the first animals with backbones?

What To Do

Use the analogy that 4.5 billion years is equal to 100 metres.



  1. Unroll the tape in an outdoor space.
  2. Have students locate the following times on the tape measure. 







  1. Have students write each event name and time on a piece of flagging tape.
  2. Using masking tape, have students attach each piece of flagging tape to its corresponding position on the 100 metre tape.
  3. Have students examine the completed time scale.


  • For a more challenging activity, have students calculate the scaled distances themselves!

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