Junior (Age 9 – 12)

Curriculum Goal

Junior: Geometry and Spatial Sense

  • Explain how protractors work, use them to measure and construct angles up to 180°, and use benchmark angles to estimate the size of other angles.


  • Whole-class introduction followed by pair-based exploratory activity.


  • History of Hypatia (Appendix A)
  • Astrolabe drawing (Appendix B, to print on card stock)
  • Astronomical object cut-outs (Appendix C)
  • Recording sheet (Appendix D)
  • Hole punch
  • String (30cm)
  • Weight
  • Tape
  • Scissors
  • Straw


  • Provide a brief history of Hypatia.
  • Invite students to construct their own astrolabes (detailed instructions).
    • Cut out the astrolabe drawing and punch a hole as indicated.
    • Cut a piece of string (~ 30cm long). Knot one end to the hole on the astrolabe and attach a weight to the other end.
    • Tape a straw on the edge indicated.
  • Instruct students on its use:
    • Hold the astrolabe so the curved part is downwards, and the 0° mark is closest to you.
    • Look along the flat edge of the astrolabe with your eye looking through the straw.
    • Point the straw at the object that you want to measure. As you tilt the astrolabe up, the weight will move to measure the degree of your angle of observation.
  • Place astronomic object cut-outs on the classroom walls and have students measure the angles of observation with a partner. Invite them to find different objects and record their angles of observation.
  • Gather for a group discussion.
    Example prompts:
    • What happens when you hold your astrolabe and look straight up?
    • What happens when you look straight ahead?
    • Does it make a difference if you measure the angle while lying down compared to if you were sitting or standing?

Look Fors

  • Can students accurately measure angels up to 180° using the astrolabe?
  • Do students see the similarities and differences between using an astrolabe and a protractor?

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