Lesson Plan

• Describe the difference between discontinuous (qualitative) and continuous (quantitative) variation.
• Explain the genetic and environmental factors that underlie each type of variation.
• Interpret phenotypic distribution graphs (bar chart vs. normal curve) and relate them to inheritance patterns.
• Classify given traits as discontinuous or continuous and justify the classification.
• Evaluate why the distinction matters for breeding programmes and evolutionary studies.

• Projector and screen
• Whiteboard and coloured markers
• Printed handouts with trait tables and graph templates
• Sample data sheets (blood‑type frequencies, human height measurements)
• Computer with spreadsheet software for quick graphing
• Sticky notes for exit tickets

Begin by asking students to think of traits that appear in clear categories (e.g., blood type) versus traits that change gradually (e.g., height). Review prior knowledge of Mendelian inheritance and polygenic traits. Explain that today’s success criteria are to differentiate the two types of variation and to illustrate each with appropriate graphs.

1. Do‑now (5'): Quick quiz on Mendelian vs. polygenic traits to activate prior knowledge.
2. Mini‑lecture (10'): Define discontinuous and continuous variation, show examples (blood groups, flower colour, height) using the projector.
3. Guided analysis (12'): Students examine a bar chart of blood‑type frequencies and a normal distribution of height; complete worksheet questions on interpreting each graph.
4. Group activity (10'): In small groups, classify a mixed list of traits and create a simple sketch of the appropriate distribution.
5. Think‑pair‑share (5'): Discuss why distinguishing the two types is important for breeding and evolutionary predictions.
6. Formative check (3'): Exit‑ticket question – “Give one example of a discontinuous trait and one of a continuous trait and state the main genetic difference.”

Recap the key features that separate discontinuous from continuous variation and highlight how each informs genetic analysis. Collect exit tickets to gauge understanding, and assign a short homework: students find a real‑world trait, classify it, and sketch the expected distribution.