| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Chemistry |
| Lesson Topic: Describe the use of zinc in galvanising as an example of a barrier method and sacrificial protection |
Learning Objective/s:
- Describe how zinc provides a physical barrier on steel surfaces.
- Explain the sacrificial (galvanic) role of zinc in protecting iron.
- Compare barrier and sacrificial methods and evaluate the advantages of galvanising.
- Interpret standard electrode potentials to predict metal reactivity in corrosion contexts.
- Apply knowledge to select appropriate corrosion‑protection methods for different environments.
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Materials Needed:
- Projector and screen
- Printed handout with cross‑section diagram of hot‑dip galvanised steel
- Zinc‑coated nail (or steel strip) and an uncoated nail
- Salt‑water solution for simple corrosion demo
- Worksheet comparing protection methods
- Clickers or quiz cards for quick checks
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Introduction:
Show a rusted nail beside a shiny zinc‑coated nail to spark curiosity about why they look different. Ask students what they already know about oxidation and electron flow in metals. Explain that by the end of the lesson they will be able to describe how zinc both blocks and sacrifices itself to protect steel.
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Lesson Structure:
- Do‑now (5'): Quick recall quiz on oxidation and corrosion using clickers.
- Mini‑lecture (10'): Introduce barrier vs sacrificial methods; present the zinc galvanising process with diagram.
- Demonstration (10'): Place zinc‑coated and uncoated nails in salt water; observe differences over a few minutes.
- Guided activity (12'): Pairs complete a worksheet comparing painting, galvanising, and cathodic protection, focusing on advantages and limitations.
- Concept check (5'): Whole‑class discussion of electrode potentials (Zn –0.76 V, Fe –0.44 V) and why zinc corrodes preferentially.
- Summary & exit ticket (3'): Students write one concise sentence describing how zinc protects steel; collect for assessment.
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Conclusion:
We revisited how zinc acts as both a physical barrier and a sacrificial anode, reinforcing the key points with the demo and worksheet findings. For the exit ticket, students recorded a single sentence summarising zinc’s protective role. Homework: research another sacrificial metal (e.g., magnesium) and write a short paragraph on its industrial use.
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