Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Physics
Lesson Topic: Know that the Milky Way is one of many billions of galaxies making up the Universe and that the diameter of the Milky Way is approximately 100000 light-years
Learning Objective/s:
  • State that the Milky Way is one of billions of galaxies in the Universe.
  • Calculate the Milky Way’s diameter in light‑years and convert it to kilometres.
  • Compare the size of the Milky Way with other astronomical objects using a scale diagram.
  • Explain why the Milky Way appears as a faint band in the night sky.
Materials Needed:
  • Projector or interactive whiteboard
  • PowerPoint/Google Slides presentation with scale diagram
  • Printed worksheet with size table and conversion problems
  • Ruler or string for hands‑on scaling activity
  • Calculator or classroom computers
 Introduction:
Begin with a striking image of the night sky showing the Milky Way and ask students what they think the faint band represents. Recall previous work on solar‑system scales and introduce today’s focus: locating the Milky Way within the vast number of galaxies and understanding its size. Students will know they can describe its diameter in light‑years and convert it to kilometres by the end of the lesson.
Lesson Structure:
  1. Do‑now (5'): Quick quiz on previous scale concepts.
  2. Teacher input (10'): Present key facts and comparative size table via slides.
  3. Scale activity (15'): Students model Earth as 1 cm and draw the Milky Way as 7 km on a large floor map (or virtual scaling tool).
  4. Guided practice (10'): Work through converting 100 000 ly to kilometres on the worksheet.
  5. Concept check (5'): Exit ticket – one sentence explaining why the Milky Way appears as a band.
  6. Summary & homework (5'): Recap and assign research on another galaxy’s diameter for comparison.
Conclusion:
Review how the Milky Way fits among billions of galaxies and reaffirm its 100 000‑light‑year diameter. Students complete an exit ticket describing one reason the Milky Way looks like a faint band. For homework, they will research the diameter of the Andromeda galaxy and prepare a brief comparison.