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

1. Which of these is a greenhouse gas? (methane / argon / nitrogen / oxygen) → methanePrompt: Cattle and rice paddies release it.
2. Before 1800, carbon dioxide in the air was about 280 ppm. Recently it was about 410 ppm. By how many ppm has it risen? → 130 ppmPrompt: Subtract the old value from the new value.
3. Climate change: which statement is NOT true? (Global average temperatures have risen since the 1800s. / A cold winter proves global warming is not happening. / Burning fossil fuels increases carbon dioxide in the atmosphere. / Planting trees can help absorb carbon dioxide.) → A cold winter proves global warming is not happening.Prompt: Is the ozone hole the same as the greenhouse effect?

• Show today's forecast and ask what it means for the class and how forecasters know.
• Share the objective: Carbon footprints and ways to cut emissions. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A car emits 120 g of CO₂ per km and is driven 15000 km in a year. How much CO₂ does it emit in the year, in kg?
• Step 1: 120 × 15000 = 1800000 g
• Step 2: 1800000 ÷ 1000 = 1800
• Step 3: So the answer is: 1800 kg
• Answer: 1800 kg
• 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. A car emits 100 g of CO₂ per km and is driven 8000 km in a year. How much CO₂ does it emit in the year, in kg? → 800 kgPrompt: Multiply grams per km by the number of km.
2. A household emits 3600 kg of CO₂ a year from energy use. Insulating the loft and walls cuts this by 50 %. How many kg of CO₂ are saved each year? → 1800 kgPrompt: Find the percentage of the original amount.

• 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 6 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. Why is reducing methane emissions an important climate action? (Methane cools the planet / Methane traps much more heat per molecule than CO₂, so cuts have a fast effect / Methane is not a greenhouse gas / Methane stays in the air forever) → Methane traps much more heat per molecule than CO₂, so cuts have a fast effectPrompt: Compare how strong and how long-lasting each gas is.
2. A car emits 150 g of CO₂ per km and is driven 15000 km in a year. How much CO₂ does it emit in the year, in kg? → 2250 kgPrompt: Multiply grams per km by the number of km.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-10.