Lesson Plan

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Lesson Plan
Grade: Year 12 Date: 25/02/2026
Subject: Physics
Lesson Topic: recall and use Hubble’s law v . H0d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units)
Learning Objective/s:
  • Describe Hubble’s law and its variables using SI units.
  • Calculate recession velocity from redshift and distance from velocity using the Hubble constant.
  • Explain how the linear v‑d relationship supports the Big Bang model.
  • Apply the law to solve exam‑style problems involving galaxy distances.
  • Evaluate the limitations of the simple linear approximation for high‑redshift galaxies.
Materials Needed:
  • Projector or interactive whiteboard.
  • Slide deck with Hubble diagram and equations.
  • Scientific calculators or spreadsheet software for SI conversions.
  • Worksheet with practice problems on Hubble’s law.
  • Handout of key constants (c, H₀, parsec, Mpc).
 Introduction:
Begin with a striking image of distant galaxies receding and ask students what redshift reveals about motion. Connect this to prior learning of the Doppler effect and the speed of light, then state that by the end of the lesson they will use Hubble’s law in SI units to determine distances and relate the result to the Big Bang theory.
Lesson Structure:
  1. Do‑now (5'): Quick quiz on Doppler shift and unit conversion.
  2. Mini‑lecture (10'): Derive v = cz for low z and introduce H₀ in SI units.
  3. Guided example (12'): Work through the provided galaxy example, calculating v and d.
  4. Pair activity (15'): Students solve a new problem using Hubble’s law, checking calculations with calculators.
  5. Concept discussion (8'): Relate linear expansion to the Big Bang, discuss supporting evidence.
  6. Check for understanding (5'): Exit ticket – one‑sentence explanation of why v = H₀d implies a finite age of the Universe.
Conclusion:
Recap that Hubble’s law links recession velocity to distance and that extrapolating the expansion backward leads to a hot, dense origin. Students write a key takeaway on a sticky note as an exit ticket. Homework: complete the worksheet on stellar radii and Hubble calculations, ensuring all quantities are expressed in SI units.