IGCSE Physics: Red Shift and Cosmology | Edexcel Modular | Unit 9 | L6

IGCSE Physics: Red Shift and Cosmology | Edexcel Modular | Unit 9 | L6

This lesson covers spec points 9.15P–9.18P (Physics only) of the Edexcel Modular IGCSE Physics
specification — red-shift of light from distant galaxies and how it provides evidence for an expanding
universe and the Big Bang.

PowerPoint includes:
• Retrieval starter reviewing the Big Bang and its evidence from L5
• Direct Instruction (I Do) — red-shift explained for a moving wave source; the change in observed
wavelength linked to the speed of recession using Δλ/λ = v/c; the observation that more distant galaxies
show greater red-shift; how this supports an expanding universe originating from the Big Bang
• Guided Practice (We Do) — three guided tasks interpreting red-shift and the expansion of the universe,
with answers revealed
• Check for Understanding — 3 MCQs on red-shift and expansion; answers on following slides
• Independent Practice (You Do) — activity sheet with exam-style questions
• Review and Reflect — exit ticket on red-shift as evidence

Activity Sheet includes:
• Exam-style questions progressing from describing red-shift to explaining how it supports an expanding
universe
• A stretch question linking red-shift–distance data to the rate of expansion
• Full mark scheme for teacher use

Note: spec points 9.15P–9.18P are Physics-only content (marked throughout).
Key relationship: Δλ/λ = v/c