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

planetary motion & gravity

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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: planetary motion & gravity

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about planetary motion & gravity. Then check against the key terms: key terms from planetary motion & gravity. 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 planetary motion & gravity.
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: planetary motion & gravity. 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 planetary motion & gravity

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about planetary motion & gravity.

Lesson 2: Core Concepts: planetary motion & gravity

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on planetary motion & gravity. Check them against the notes below.

Main Content (35 minutes)

Key Fact: Kepler's first law: planets orbit in ellipses with the Sun at one focus
Key Fact: Kepler's second law: a line joining a planet and the Sun sweeps equal areas in equal times (planets move faster at perihelion, slower at aphelion)
Key Fact: Kepler's third law: T² ∝ a³ — the square of the orbital period is proportional to the cube of the semi-major axis
Key Fact: Newton's law of gravitation: F = GMm/r² — gravitational force is proportional to the product of masses and inversely proportional to the square of the distance
Key Fact: Orbital speed depends on distance from the central body: closer objects orbit faster
Key Fact: Escape velocity is the minimum speed needed to escape a body's gravitational field: v = √(2GM/r)

Practice (10 minutes)

Q: explain the key ideas of planetary motion & gravity

Answer:

Plenary (5 minutes)

Explain Back

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

Lesson 3: Application: planetary motion & gravity

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from planetary motion & gravity. 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: planetary motion & gravity

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 planetary motion & gravity from the exam board past paper finder (see Resources), then mark it against the scheme.

Exam Tips: Kepler's 3rd law calculations: use Earth as reference (a=1 AU, T=1 year) for simplicity | F = GMm/r² — remember: doubling distance quarters the force (inverse square law) | AQA specifically tests Kepler's laws — know all three by name and content | For Edexcel, be prepared to apply Kepler's 3rd law to calculate orbital periods
Common Errors: ✗ Planets orbit in perfect circles ✓ Kepler's first law states orbits are ellipses with the Sun at one focus, not the centre ✗ Gravity is stronger at greater distances ✓ Gravitational force decreases with the square of the distance (inverse square law) ✗ Kepler's 3rd law says T = a³ ✓ Kepler's 3rd law says T² ∝ a³ (the square of the period is proportional to the cube of the semi-major axis)
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how planetary motion & gravity connects to another Astronomy topic you have studied
  • Real-world: research one real-world use or example of planetary motion & gravity
  • Critical: "What are the limitations of the models used in planetary motion & gravity?"

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)