Gravity Shapes Our Universe

Overview

Students use selected clips from Our Universe, especially “Force of Attraction”, to investigate gravity as a non-contact force and a force of attraction between masses. They connect observations of penguins, Earth and celestial bodies to force diagrams, mass, weight and the role of gravity in motion.

Learning intentions

• WALT explain gravity as a non-contact force that attracts objects with mass.
• WALT distinguish between mass and weight.
• WALT represent gravitational and other forces using force arrows and free-body diagrams.
• WALT use evidence from a documentary to explain how gravity affects objects on Earth and in space.

Success criteria

• I can describe gravity as an attractive, non-contact force.
• I can explain that weight is the force of gravity acting on an object and is measured in newtons.
• I can draw and label appropriate force arrows, including the direction of gravity.
• I can use an observation from the documentary to support a scientific explanation.

Curriculum links

• Physical Science — Motion and Forces: gravity governs the behaviour and interactions of matter.
• Physical Science — Non-contact forces: gravity pulls objects towards the centre of Earth.
• Physical Science — Non-contact forces: weight is the force of gravity acting on an object due to its mass.
• Motion and Forces — The effect of forces: representing common forces with free-body diagrams and identifying unbalanced forces.

The lesson supports the Science capabilities of interpreting representations, gathering and interpreting data, and communicating explanations, alongside thinking and participating and contributing.

Lesson structure (60 minutes)

1. 0–5 min · Hook and prediction. Open with the gravity hook slide showing a penguin standing on a steep Antarctic slope and ask, “What keeps it on the surface rather than flying into space?” Students write an individual prediction, then share with a partner. Introduce the focus question: “How does gravity shape life and motion?”

2. 5–13 min · Documentary observation. Play a teacher-selected 3–4 minute excerpt from the “Force of Attraction” episode of Our Universe, focusing on gravity shaping the universe and influencing the movement and survival of king penguins. Students complete the observation column in the gravity documentary worksheet, recording one event, the object affected and the direction of the gravitational pull. Pause once to clarify that the documentary is evidence to interpret, not a complete scientific explanation.

3. 13–25 min · Direct teaching. Use the gravity teaching slides to explain that gravity is an attractive, non-contact force between objects with mass. Clarify that Earth’s gravity pulls objects towards Earth’s centre, while the Sun, planets and stars also attract one another. Model the distinction: mass is the amount of matter, measured in kilograms; weight is gravitational force, measured in newtons. Introduce the relationship weight = mass × gravitational field strength, using 10 N/kg as an appropriate near-Earth classroom approximation. Students complete the key-term and calculation prompts on the worksheet.

4. 25–40 min · Force-diagram workshop. Model a free-body diagram for a penguin standing still: weight acts downwards and the support force from the ground acts upwards. In pairs, students complete diagrams on the worksheet for a falling object, a person standing on Earth and a planet orbiting a star. They add arrows, labels and a short statement about whether the forces are balanced or unbalanced. Circulate and ask, “What object is your diagram showing?” and “What evidence tells you the arrow points in that direction?”

5. 40–51 min · Evidence and explanation. Play a second short excerpt from the documentary, selected to show gravity operating beyond the immediate Earth–surface example, such as gravity’s role in celestial systems. Refer to the evidence discussion slides and ask students to identify what gravity is doing, what other force or motion may be involved, and whether the evidence shows attraction, support or changing motion. Pairs complete the worksheet’s CER response: claim, evidence from the documentary, and scientific reasoning.

6. 51–60 min · Review and exit assessment. Display the plenary slides and revisit the focus question. Students complete the final worksheet questions independently: “Why do astronauts still have mass in orbit?” and “Why can their apparent weight be much smaller?” Collect worksheets and invite two students to share a carefully worded explanation. Address the misconception that gravity only exists on Earth or only acts on falling objects.

Resources

• Teacher-selected excerpts from the “Force of Attraction” episode of Our Universe
• gravity and documentary discussion slide deck
• the gravity documentary worksheet
• Projector, speakers and reliable access to the documentary
• Whiteboard and markers
• Calculators
• Science notebooks or pens
• Diagram example prepared on the board

Assessment

• Listen to predictions and partner explanations for the ideas that gravity is downward, contact-based or only present during falling.
• Check worksheet observations, mass–weight calculations and free-body diagrams during pair work; question students about object choice, arrow direction and balanced forces.
• Use the final CER response and independent questions as an exit assessment. Look for accurate use of “mass”, “weight”, “newtons”, “non-contact” and “attraction”.

Differentiation

• Provide a word bank and sentence starters on the worksheet: “Gravity is…”, “The evidence shows…”, and “The force arrow points… because…”. Pre-teach mass, weight, force, attraction, orbit and support force with visuals.
• For students needing support, provide partially completed force diagrams, allow verbal responses before writing, and pair students strategically. Keep documentary clips short, pause for processing, and enable subtitles where available.
• For EAL learners, explicitly contrast everyday “weight” with the scientific meaning and use labelled diagrams, gestures and repeated sentence structures.
• Extend confident students by asking them to compare Earth and Moon weight using different gravitational field strengths, or explain why an orbiting object is continuously falling towards a star while moving sideways.