Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Physics
Lesson Topic: Know that the Sun contains most of the mass of the Solar System and this explains why the planets orbit the Sun
Learning Objective/s:
  • Describe the mass distribution of the Solar System, emphasizing that the Sun holds about 99.86 % of the total mass.
  • Explain how the Sun’s dominant mass determines planetary orbits using Newton’s law of gravitation.
  • Calculate the orbital speed of a planet given its distance from the Sun.
  • Interpret a scale diagram of the Solar System to illustrate the Sun’s gravitational influence.
Materials Needed:
  • Projector or interactive whiteboard
  • Slide deck with mass‑distribution table and diagram
  • Printed worksheet with quick‑check questions
  • Calculator or online computation tool
  • Ruler or string for a scale‑model activity (optional)
  • Whiteboard and markers
 Introduction:
Begin with a striking fact: the Sun holds 99.86 % of the Solar System’s mass. Ask students to recall how gravity keeps planets in orbit and why the Sun’s mass matters. Explain that by the end of the lesson they will be able to describe the mass distribution, apply Newton’s law to orbital motion, and solve a simple speed calculation.
Lesson Structure:
  1. Do‑now (5 min): Quick‑check quiz on mass percentages and the gravitational‑force formula displayed on the board.
  2. Mini‑lecture (10 min): Present the mass‑distribution table, highlight the Sun’s dominance, and link it to Newton’s law of universal gravitation.
  3. Guided derivation (10 min): Work through the orbital‑speed equation on the whiteboard while students complete the corresponding worksheet steps.
  4. Interactive scale model (8 min): Students create a relative‑size diagram of the Solar System using string/ruler, emphasizing the Sun’s size.
  5. Collaborative problem solving (10 min): In pairs calculate Earth’s orbital speed using the given values; teacher circulates to provide feedback.
  6. Exit ticket (5 min): Students write one sentence summarising why planets orbit the Sun rather than each other.
Conclusion:
Summarise that the Sun’s overwhelming mass creates the gravitational centre that fixes planetary speeds and paths. Collect exit tickets to check understanding, and assign a homework task to research another massive body’s influence in its system. Remind students to review the orbital‑speed formula for upcoming tests.