Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Chemistry
Lesson Topic: Describe how the greenhouse gases carbon dioxide and methane cause global warming, limited to: (a) the absorption, reflection and emission of thermal energy (b) reducing thermal energy loss to space
Learning Objective/s:
  • Describe how CO₂ and CH₄ absorb infrared radiation and re‑emit it in all directions.
  • Explain how reduced atmospheric emissivity alters Earth’s thermal energy balance.
  • Compare the infrared absorption bands, atmospheric lifetimes and global‑warming potentials of CO₂ and CH₄.
  • Analyse how greenhouse gases lower thermal energy loss to space through increased optical depth and feedback mechanisms.
Materials Needed:
  • Projector and computer
  • PowerPoint slides with energy‑flow diagram
  • Printed worksheet containing spectra tables and calculation tasks
  • Online greenhouse‑gas simulation (e.g., PhET)
  • Whiteboard and markers
  • Exit‑ticket cards or digital quiz tool
 Introduction:

Begin with a recent headline about rising global temperatures to capture interest. Ask students to recall how the Earth receives short‑wave solar energy and emits long‑wave infrared radiation. State that by the end of the lesson they will be able to explain how CO₂ and CH₄ modify this energy flow and identify the specific ways they reduce heat loss to space.
Lesson Structure:
  1. Do‑Now (5’) – Quick quiz on short‑wave vs. long‑wave radiation on the board.
  2. Mini‑lecture with slides (10’) – Cover absorption, re‑emission, and back‑radiation of CO₂ and CH₄.
  3. Interactive simulation (8’) – Students explore photon‑molecule interactions using an online model.
  4. Group analysis (12’) – Compare CO₂ and CH₄ tables; discuss absorption bands, lifetimes, and GWP.
  5. Guided calculation (10’) – Apply the energy‑balance equation to show how increased greenhouse gases lower emissivity.
  6. Check for Understanding (5’) – Exit‑ticket: one sentence describing how greenhouse gases reduce thermal energy loss to space.
Conclusion:

Summarise the key mechanisms—absorption, re‑emission, and reduced emissivity—that cause warming. Collect exit tickets to gauge understanding and assign a short homework: research a local source of CO₂ or CH₄ and suggest one mitigation action.