• Quick retrieval from earlier learning (Gravity). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. People in Australia do not fall off the Earth. Why? (Australia has no gravity / They hold on tightly / They wear heavy shoes / Gravity pulls everyone towards the centre of the Earth) → Gravity pulls everyone towards the centre of the EarthPrompt: "Down" means towards the centre of the Earth, wherever you are.
2. Gravity: which statement is true? (Gravity only acts on things that are falling. / There is no gravity in space. / Gravity is a force that attracts objects with mass towards each other. / Heavy objects always fall faster than light ones.) → Gravity is a force that attracts objects with mass towards each other.Prompt: What keeps the Moon going round the Earth?
3. Gravity: which statement is NOT true? (Astronauts float in the space station because there is no gravity there. / Gravity is weaker on the Moon than on Earth. / Without air resistance, a heavy and a light object fall at the same rate. / Gravity is a force that attracts objects with mass towards each other.) → Astronauts float in the space station because there is no gravity there.Prompt: Why does the space station stay in orbit?

• Drop a sheet of paper and a scrunched-up sheet together and ask why one falls faster.
• Share the objective: Mass and weight (W = mg). Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: What is the weight of a 75 kg object on Earth? Use g = 9.8 N/kg.
• Step 1: W = 75 × 9.8 = 735
• Step 2: So the answer is: 735 N
• Answer: 735 N
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. What is the weight of a 20 kg object on Earth? Use g = 9.8 N/kg. → 196 NPrompt: weight = mass × gravitational field strength (W = m g)
2. An astronaut's mass is 40 kg. Gravitational field strength on the Moon is 1.6 N/kg. What would their weight be there, in N? → 64 NPrompt: Mass stays the same everywhere; weight changes.

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. An astronaut's mass is 10 kg. Gravitational field strength on Mars is 3.7 N/kg. What would their weight be there, in N? → 37 NPrompt: Mass stays the same everywhere; weight changes.
2. What is the weight of a 5 kg object on Earth? Use g = 9.8 N/kg. → 49 NPrompt: weight = mass × gravitational field strength (W = m g)

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.