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

1. What evidence suggests the continents were once joined? (matching fossils and rock layers on continents far apart / the same weather on every continent / the oceans are salty / all continents are the same size) → matching fossils and rock layers on continents far apartPrompt: The same land reptile fossils are found in Africa and South America.
2. Two plates move apart at about 2.5 cm per year. How far apart will they move in 1 000 years, in kilometres? (1 km = 100 000 cm) → 0.025 kmPrompt: First find the distance in cm.
3. Plate tectonics: which statement is NOT true? (The Earth's crust is broken into large pieces called tectonic plates. / Plates move a few centimetres each year. / Mountains such as the Himalayas formed where plates collided. / Volcanoes only form in hot countries.) → Volcanoes only form in hot countries.Prompt: How fast do your fingernails grow? Plates move at about that speed.

• Pass round different rocks and ask how each one might have formed.
• Share the objective: Measure earthquakes and reduce their risks. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: On the magnitude scale, each whole number up means the ground shaking (wave amplitude) is 10 times larger. How many times larger is the shaking in a magnitude 8 earthquake than in a magnitude 6?
• Step 1: 8 − 6 = 2
• Step 2: 10^2 = 100
• Step 3: So the answer is: 100
• Answer: 100
• 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. On the magnitude scale, each whole number up means the ground shaking (wave amplitude) is 10 times larger. How many times larger is the shaking in a magnitude 5 earthquake than in a magnitude 4? → 10Prompt: How many steps up the scale is it?
2. Some countries send phone alerts seconds before strong shaking arrives. How is this possible? (Sensors detect the faster, weaker first waves and send warnings before slower damaging waves arrive / Radio waves are slower than seismic waves / They predict quakes days ahead / Phones feel the earthquake first) → Sensors detect the faster, weaker first waves and send warnings before slower damaging waves arrivePrompt: Electronic signals travel far faster than seismic waves.

• 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. Earthquakes: which statement is NOT true? (The point on the surface above an earthquake's origin is the epicentre. / Each step up in magnitude releases about 32 times more energy. / Earthquakes only happen in hot countries. / Undersea earthquakes can cause tsunamis.) → Earthquakes only happen in hot countries.Prompt: Is the magnitude scale linear?
2. What instrument records earthquake waves? (a seismometer / an anemometer / a barometer / a thermometer) → a seismometerPrompt: "Seismic" means to do with earthquakes.

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