Lesson Plan

• Describe the purpose and main components of a function (definition, parameters, return value, scope).
• Explain how to write and invoke a function using Python‑style syntax.
• Apply correct parameter passing and return statements to solve coding problems.
• Identify and correct common function errors such as missing returns or argument mismatches.

• Projector or interactive whiteboard
• Computer lab with Python IDE (e.g., IDLE, VS Code)
• Printed handout of function syntax and example code
• Worksheet with practice questions
• Access to an online Python interpreter (optional)

Begin with a quick discussion of how everyday apps (maps, calculators) rely on reusable blocks of code. Review students’ prior knowledge of variables and simple statements, then pose the success criteria: by the end of the lesson they will be able to write, call, and debug a function in Python.

1. Do‑now (5'): Write a one‑line Python expression to calculate the area of a circle; share answers.
2. Mini‑lecture (10'): Introduce function concepts, terminology, and flowchart diagram.
3. Guided demonstration (15'): Define circle_area(radius), run it, and discuss parameters and return value.
4. Pair activity (15'): Students create max_of_three(a,b,c) on the worksheet, test with sample inputs, and receive teacher feedback.
5. Error‑spotting (10'): Review common mistakes; students debug a faulty function example.
6. Exit ticket (5'): Write a correct function definition for temperature conversion and note one error to avoid.

Recap the four key steps of defining and using a function and highlight how proper scope and return statements improve code reliability. Collect exit tickets as a quick retrieval check, and assign homework: students must write a function that converts Fahrenheit to Celsius and include at least one test case.