Lesson Plan

• Describe the three domains of life and their defining characteristics.
• Compare cell structure, membrane composition and cell‑wall features across Archaea, Bacteria and Eukarya.
• Explain how rRNA sequencing is used to distinguish the domains.
• Interpret a simplified phylogenetic tree that shows the relationships among the domains.

• Projector and screen
• PowerPoint/Google Slides presentation
• Handout with domain comparison table
• Whiteboard and markers
• Sticky notes for exit tickets
• Kahoot or quiz worksheet
• Optional: microscope slides of extremophiles

Begin with a striking image of microbes thriving in hot springs to hook students’ curiosity. Ask them what they already know about prokaryotes versus eukaryotes, linking this to the upcoming classification system. Explain that by the end of the lesson they will be able to describe the three domains and identify the key traits that separate them.

1. Do‑now (5'): Quick quiz on differences between prokaryotic and eukaryotic cells.
2. Mini‑lecture with slides (10'): Introduce the three‑domain system and the role of rRNA sequencing.
3. Group activity – fill‑in the comparison table (12'): Students complete missing features for each domain using the handout.
4. Phylogenetic tree discussion (8'): Analyze a simplified tree and place the domains in evolutionary context.
5. Case study – extremophilic Archaea (10'): Examine adaptations such as ether‑linked lipids and discuss ecological significance.
6. Formative check (5'): Kahoot quiz or exit‑ticket on key characteristics.

Summarise the defining traits of Archaea, Bacteria and Eukarya and reinforce how molecular data underpins the classification. Collect exit tickets where students write one fact they found most surprising. For homework, assign a brief research task: find an organism from each domain and note its unique adaptation.