We tried this activity, 'A time-line in your own backyard' using toilet paper for the geological time-line: with a roll of 600 segments we covered the evolution of pluricellular life (1 segment = 1 million years). The positioning of milestones along the time-line is a good starting point for discussion. You only need a school-yard, good weather and no wind. These students are 16 years old and enjoyed the activity.
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