• 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 is an effect of climate change? (the Earth stopping rotating / more oxygen in the air / rising sea levels as ice melts and seawater expands / the end of all weather) → rising sea levels as ice melts and seawater expandsPrompt: What happens to glaciers when it warms?
2. Before 1800, carbon dioxide in the air was about 280 parts per million (ppm). Recently it was about 400 ppm. By what percentage has it increased? Give a whole number. → 43 %Prompt: First find the increase.
3. Climate change: which statement is NOT true? (Without any greenhouse effect, Earth would be too cold for most life. / Planting trees can help absorb carbon dioxide. / Global average temperatures have risen since the 1800s. / Oxygen is the main greenhouse gas.) → Oxygen is the main greenhouse gas.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 180 g of CO₂ per km and is driven 5000 km in a year. How much CO₂ does it emit in the year, in kg? → 900 kgPrompt: Multiply grams per km by the number of km.
2. A household emits 4000 kg of CO₂ a year from energy use. Insulating the loft and walls cuts this by 20 %. How many kg of CO₂ are saved each year? → 800 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. A car emits 150 g of CO₂ per km and is driven 5000 km in a year. How much CO₂ does it emit in the year, in kg? → 750 kgPrompt: Multiply grams per km by the number of km.
2. A household emits 2400 kg of CO₂ a year from energy use. Fitting solar panels cuts this by 25 %. How many kg of CO₂ are saved each year? → 600 kgPrompt: Find the percentage of the original amount.

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