Lesson Plan

• Describe the mechanism by which penicillin inhibits bacterial cell‑wall synthesis.
• Explain why antibiotics are ineffective against viruses.
• Compare key structural differences between bacteria and viruses relevant to antimicrobial action.
• Analyse how inhibition of penicillin‑binding proteins leads to bacterial lysis.
• Evaluate the implications of antibiotic specificity for treating infections.

• Projector and screen for diagrams
• PowerPoint slides illustrating penicillin mechanism
• Handout with bacteria vs. viruses summary table
• Whiteboard and markers
• Microscopy images of bacterial cell walls (optional)
• Worksheet with case‑study questions

Begin with a quick poll: “Which medicines have you taken for infections?” This activates prior knowledge of antibiotics. Explain that today we will uncover how penicillin attacks bacteria and why the same drugs fail against viruses. Students will know the success criteria: they can diagram penicillin’s target and list reasons antibiotics don’t work on viruses.

1. Do‑now (5’) – Students list common antibiotics they know on a sticky note.
2. Mini‑lecture (10’) – Present slides on β‑lactam structure and PBPs, using a diagram.
3. Guided analysis (10’) – Walk through the binding mechanism; students label a diagram of penicillin binding.
4. Comparative activity (10’) – In pairs, complete a table contrasting bacteria and viruses; teacher checks understanding.
5. Interactive simulation (5’) – Quick online animation of bacterial lysis.
6. Formative check (5’) – Exit ticket: write one reason antibiotics don’t affect viruses.
7. Summary discussion (5’) – Review key points and address misconceptions.

Recap the steps by which penicillin disrupts cell‑wall synthesis and why viruses lack those targets. Students complete an exit ticket summarising one key difference. Assign a short homework: research an antiviral drug and compare its target to that of penicillin.