Overview

• Duration: 60 minutes
• Class: Year 7 (ages 11-12)
• Class size: 30 students
• Subject: Science
• Topic: Gravity
• Curriculum link:
  • National Curriculum for England, KS3 Science – Physics: Forces.
  • Pupils should be taught to:
    • Understand that forces act at a distance (gravity, magnetic forces).
    • Recognise gravity as a force pulling objects towards the Earth (and other celestial bodies).
    • Use the idea of gravitational fields to explain attractions between masses.
    • Understand how gravitational field strength depends on mass and distance (qualitatively).

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Learning Objectives

By the end of the lesson, students will be able to:

1. Define gravity as a force that attracts two masses towards each other.
2. Describe how gravitational field strength changes with mass: larger masses produce stronger gravitational fields.
3. Describe how gravitational field strength changes with distance: gravitational field strength decreases as distance from a mass increases.

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Curriculum Reference

• Programme of Study (Physics – Forces):
  • “Students should learn about contact and non-contact forces, such as gravity, and understand the concept of fields.”
  • “Be able to explain gravitational fields as regions where a mass experiences a force.”
  • “Describe gravitational attraction qualitatively, including the effect of distance and mass on the strength of gravity.”

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Materials Needed

• Globe or large ball to represent Earth
• Small balls (tennis balls or foam balls)
• Large sheet or stretchy fabric (e.g., lycra or old trampoline fabric)
• Metal or plastic weights
• Worksheets with scenarios for discussion
• Whiteboard and markers
• Stopwatch or timer (for activity timing)
• Projector or computer for short video demonstration (optional)

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Lesson Structure

1. Introduction (10 mins)

• Starter question: Write on board: "What is gravity?" Ask students for quick ideas or examples in pairs for 2 minutes.
• Teacher explanation: Define gravity as a force of attraction between objects that have mass. Explain gravity pulls objects towards the Earth and exists everywhere there is mass.
• Show a simple demonstration: Drop two differently sized balls (e.g. tennis ball and paper ball) to highlight they fall due to gravity.

Curriculum link: Introduce the idea of a force acting at a distance and the concept of gravitational attraction.

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2. Exploring Gravitational Field Strength and Mass (15 mins)

• Concept explanation: Introduce gravitational field strength as a measurement of how strong gravity is at a location; stronger near big masses.

• Use the globe and small balls: hold the globe representing Earth and the smaller balls as satellites or objects.

• Explain that the Earth's gravitational field pulls objects towards it. Larger mass = stronger pull.

• Activity: Students feel the “pull” or attraction metaphorically by discussing which planet they think would have stronger gravity based on its size (e.g., Earth vs. Moon). Use images or quick mental math comparisons.

• Group discussion: Why does a larger mass mean stronger gravity? Introduce intuitive concepts like “more mass, more pull.”

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3. Activity: Gravity and Distance (15 mins)

• Demonstration: Stretch the fabric over a frame or hold it tight (stretchy surface represents space). Place a heavy weight in the middle – creating a dip simulating gravity’s effect on spacetime.

• Roll smaller balls (satellites) around the heavy ball at different distances. Notice how the closer balls curve quicker around it, and the further ones move slower or in straighter lines.

• Explain: The further away an object is, the weaker the gravitational pull it feels. This can be described as gravitational field strength decreasing with distance.

• Student practical: In groups of 5, students try rolling balls on the fabric at multiple distances and observe. Fill in a worksheet predicting and recording observations about gravitational attraction at increasing distances.

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4. Recap and Consolidation (10 mins)

• Use a quick quiz on the whiteboard:
  • Define gravity.
  • How does mass affect gravity?
  • How does distance affect gravity?
• Ask pairs to write a short explanation linking these answers together.
• Go through answers as a class, clarifying misconceptions.

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5. Assessment: Exit Ticket (10 mins)

• Each student completes a short written task:

  • Write a paragraph to explain gravity, including the effects of mass and distance on gravitational field strength. Use examples from the lesson.
  • Alternatively, students label a diagram of a planet and satellites showing where gravitational field strength is strongest and weakest.

• Collect these for formative assessment. Use this to identify who has met the learning objectives for this lesson.

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Differentiation

• For lower ability: Provide sentence starters, diagrams with labels to fill in, and a glossary of key terms (gravity, force, mass, distance).
• For higher ability: Ask students to predict what happens to gravitational field strength on smaller or larger planets compared to Earth, and consider why astronauts feel “weightless” in orbit.

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Homework Suggestion

Ask students to research a planet in the Solar System and write 3 facts about its gravity. They should include how its mass compares to Earth’s and how distance from the sun affects objects in its gravitational field.

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Teaching Tips

• Use real-world examples (planets, moons, satellites) to make gravity relatable.
• Foster curiosity by encouraging “what if” questions: What if Earth’s mass changed? What if we were twice as far from Earth?
• Encourage peer discussion during practical activities to support collaborative learning.

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This lesson plan cleanly aligns with the KS3 National Curriculum for England, specifically addressing the specified learning outcomes related to gravitational forces, fields, and factors affecting gravitational field strength. It blends direct teaching, inquiry-based learning, and hands-on activity for effective understanding.