| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: explain how speciation may occur as a result of genetic isolation by: geographical separation (allopatric speciation), ecological and behavioural separation (sympatric speciation) |
Learning Objective/s:
- Describe the mechanisms of allopatric and sympatric speciation caused by genetic isolation.
- Explain how geographical barriers, ecological niches, and behavioural differences lead to reproductive isolation.
- Analyse examples such as Galápagos finches, apple maggot fly, and polyploid plants to illustrate speciation processes.
- Evaluate the genetic consequences (drift, selection, polyploidy) associated with each speciation mode.
- Apply knowledge to answer exam‑style questions on speciation.
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Materials Needed:
- Projector and screen for diagrams.
- Whiteboard and markers.
- Printed worksheets with comparison tables and example scenarios.
- Images of Galápagos finches, apple maggot life cycle, and polyploid plant diagrams.
- Student laptops or tablets for an interactive quiz (optional).
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Introduction:
Begin with a quick think‑pair‑share: “What would happen to two groups of animals if a river suddenly split their habitat?” Review prior knowledge of gene flow and natural selection, then outline today’s success criteria: students will be able to describe and compare allopatric and sympatric speciation and apply examples.
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Lesson Structure:
- Do‑Now (5') – Students answer a short prompt on barriers to gene flow on a sticky note.
- Mini‑lecture (10') – Overview of genetic isolation, allopatric vs sympatric mechanisms with slides.
- Case Study Exploration (15') – Small groups analyse the Galápagos finch example; create a quick sketch of island separation.
- Interactive Activity (15') – Groups examine the apple maggot fly scenario; identify ecological and behavioural isolating factors on a worksheet.
- Polyploidy Demonstration (10') – Teacher models chromosome duplication using visual aids; discuss plant speciation.
- Comparison Table Completion (10') – Whole class fills a table contrasting the two speciation types, checking understanding.
- Formative Quiz (5') – Kahoot or similar to assess key concepts.
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Conclusion:
Summarise how physical barriers and ecological/behavioural differences each generate genetic isolation, reinforcing the key examples discussed. Students complete an exit ticket stating one similarity and one difference between the speciation modes. Assign homework to draft a brief answer to one of the sample exam questions.
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