Lesson Plan

• Describe how independent assortment and crossing‑over generate genetic variation in gametes.
• Explain why the random fusion of sperm and ovum results in genetically unique individuals.
• Calculate the number of possible gamete and zygote genotypes for a given haploid chromosome number.
• Evaluate the significance of genetic variation for evolution and population resilience.

• Projector and screen
• Whiteboard and markers
• Handout with gamete‑combination tables
• Colored beads or cards to model chromosome segregation
• Worksheets for genotype calculations
• Exit‑ticket cards

Begin with a quick think‑pair‑share: “Why do siblings look different?” Connect this to prior learning on meiosis. State that today’s success criteria are to describe the mechanisms that randomise gamete composition and to predict the resulting genetic diversity.

1. Do‑now (5'): Students answer a question on sibling differences and discuss.
2. Mini‑lecture (10'): Review haploid/diploid cells, independent assortment, and crossing‑over with diagrams.
3. Interactive modelling (15'): Use colored beads/cards to simulate chromosome segregation and random fusion; record possible gamete combos.
4. Guided calculation (10'): Work through 2ⁿ and 2²ⁿ examples for humans and a simple species.
5. Table analysis (10'): Examine the provided gamete‑combination table, identify patterns, and discuss consequences.
6. Check for understanding (5'): Quick quiz via clickers or show of hands.
7. Consolidation activity (5'): Complete a worksheet summarising the mechanisms.

Recap that independent assortment and crossing‑over randomise gamete chromosomes, and their fusion creates vast genetic diversity. Students finish an exit ticket describing one way this variation benefits populations. For homework, read a short article on natural selection using genetic variation.