Eras & Periods


  • To discover how long ago dinosaurs lived.
  • To discover what a time line is.
  • To discover the difference between eras and periods.
  • To discover the era of the dinosaurs.
  • To discover the periods of the dinosaurs.
  • To discover the era of today.


  • Discussion of time line.
  • Use example of a student’s life on board (date of birth through present day), label any special events student had.
  • Discuss that Earth has a time line.
  • Introduce Earth’s time line on board (starting date through present day).
  • Divide into 2 eras (Mesozoic & Cenozoic) and the Mesozoic into 3 periods (Triassic, Jurassic, & Cretaceous), include dates.
  • Compare time line of Earth to calendar to summarize.