Lesson Plan

• Describe Hubble’s Law and the meaning of the Hubble constant.
• Explain how rearranging Hubble’s Law yields the age estimate d ⁄ v = 1⁄H₀.
• Calculate an approximate age of the Universe using a given H₀ value.
• Interpret the age estimate as evidence for a single‑point origin (Big Bang).
• Evaluate the limitations of the simple 1⁄H₀ age calculation.

• Projector and screen
• Whiteboard and markers
• Scientific calculators or spreadsheet software
• Worksheet with Hubble‑constant table and conversion steps
• Graph paper or digital plotting tool for v vs. d
• Handout summarising the derivation and significance

Begin with a striking image of distant galaxies receding from us to spark curiosity about the expanding Universe. Ask students to recall how speed, distance and proportionality were used in the previous lesson on motion. State that by the end of class they will be able to derive a simple age of the Universe and explain why this supports a single‑origin model.

1. Do‑now (5'): Quick quiz on speed‑distance relationships and proportional reasoning.
2. Mini‑lecture (10'): Introduce Hubble’s Law, derive d/v = 1/H₀, and show a v‑vs‑d diagram.
3. Guided calculation (12'): Students convert H₀ = 70 km s⁻¹ Mpc⁻¹ to s⁻¹ and compute the age (≈14 billion yr) using the worksheet.
4. Data interpretation activity (10'): Using the provided table, compare ages for H₀ = 67, 70, 74 and discuss implications for the Big Bang.
5. Class discussion (8'): Highlight current H₀ measurement tensions and the limits of the 1/H₀ estimate.
6. Exit ticket (5'): Write one sentence explaining how the age estimate supports a single‑point origin.

Summarise that the simple inversion of the Hubble constant gives a first‑order age of ~14 billion years, reinforcing the idea of a hot, dense beginning. Collect exit tickets and remind students to complete a short homework task: research the current “Hubble tension” and write a 150‑word summary.