Homeschool Guide: These lesson plans are a guide for parents. Content may contain errors — always cross-reference with official exam board specifications.

the big bang & expansion

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: the big bang & expansion

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about the big bang & expansion. Then check against the key terms: key terms from the big bang & expansion. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: key terms from the big bang & expansion.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: the big bang & expansion. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Astronomy because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: explain the key ideas of the big bang & expansion

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about the big bang & expansion.

Lesson 2: Core Concepts: the big bang & expansion

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on the big bang & expansion. Check them against the notes below.

Main Content (35 minutes)

Key Fact: The Big Bang theory states the universe began from an extremely hot, dense singularity ~13.8 billion years ago
Key Fact: Hubble's law: v = H₀d — recession velocity is proportional to distance; further galaxies recede faster
Key Fact: Cosmological redshift occurs because space itself is expanding, stretching light to longer wavelengths
Key Fact: The cosmic microwave background (CMB) is the afterglow of the Big Bang, at ~2.7 K
Key Fact: The CMB is remarkably uniform, with tiny fluctuations that correspond to the seeds of large-scale structure
Key Fact: Olbers' paradox (why the sky is dark at night) is resolved by the finite age and expansion of the universe

Practice (10 minutes)

Q: explain the key ideas of the big bang & expansion

Answer:

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: the big bang & expansion

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from the big bang & expansion. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Work through the practice questions on the revision notes page for this topic.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: the big bang & expansion

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Exam-Style Question

Attempt a past-paper style question on the big bang & expansion from the exam board past paper finder (see Resources), then mark it against the scheme.

Exam Tips: Hubble's law: v = H₀d — know the formula and units | CMB temperature: ~2.7 K (nearly 3 K) — this is a common recall question | Three key pieces of evidence for the Big Bang: redshift, CMB, abundance of light elements (H, He) | Olbers' paradox is specifically on the Edexcel specification
Common Errors: ✗ Redshift means galaxies are moving through space away from us ✓ Cosmological redshift is caused by space itself expanding — galaxies are carried apart by expanding space, not flying through it ✗ The Big Bang was an explosion in space ✓ The Big Bang was an expansion OF space itself — there was no pre-existing space for it to explode into ✗ The CMB comes from the Big Bang itself ✓ The CMB comes from ~380,000 years after the Big Bang, when the universe had cooled enough for atoms to form and become transparent to radiation
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how the big bang & expansion connects to another Astronomy topic you have studied
  • Real-world: research one real-world use or example of the big bang & expansion
  • Critical: "What are the limitations of the models used in the big bang & expansion?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)