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Year 10 Computer Science: Python while loops lesson pack

A complete, ready-to-teach GCSE lesson on python while loops. Below is a real sample of what ChalkHour makes: the full pack adds three levels of worksheet, model answers, a teaching explainer and print-ready PDF and Word files.

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Real sample

Python While Loops: Indefinite Iteration

This lesson introduces Year 10 students to indefinite iteration using Python 'while' loops. Students will learn the syntax, how to control loop execution using conditions, and how to avoid the common pitfall of infinite loops. The lesson covers both counter-controlled and sentinel-controlled loops.

Learning objectives

  • Explain the purpose of a while loop as a form of indefinite iteration.
  • Identify and fix common errors in while loops, such as infinite loops and off-by-one errors.
  • Construct a Python program that uses a while loop to validate user input.
  • Trace the value of variables through multiple iterations of a while loop.

Lesson plan (60 minutes)

  1. Introduction · 5 min

    Starter: Retrieval practice on 'If statements' and comparison operators (==, !=, <, >).

  2. Teaching · 10 min

    Teacher Explanation: Introduction to while loops, syntax, and the concept of 'indefinite iteration'.

  3. Teaching · 10 min

    Live Coding: Teacher demonstrates a basic counter loop and a user-input validation loop.

  4. Independent Practice · 20 min

    Differentiated Activity: Students work through Support, Core, or Stretch worksheets.

  5. Plenary · 5 min

    Debug Challenge: Students identify errors in 3 broken code snippets on the board.

  6. Assessment · 10 min

    Check for Understanding: 8-question multiple-choice quiz.

Key vocabulary

Iteration
Repeating a section of code multiple times.
Indefinite Iteration
A loop where the number of repeats is not known in advance.
Infinite Loop
A loop that never ends because the condition never becomes False.
Sentinel Value
A specific value used to signal the end of a loop (e.g., typing 'quit').
Increment
Increasing a variable by a set amount (usually 1).

Core worksheet (first questions)

  1. Explain the term 'indefinite iteration' in your own words.
  2. True or False: A 'while' loop will always run at least once. Explain your answer.
  3. Find the error: \nx = 10\nwhile x == 10:\n print("Hello")\n(The code prints Hello forever. Why?)
  4. Write a short program that asks a user for a password and keeps asking until they type "coding".

Quiz (sample)

  1. 1. When does a 'while' loop execute its block of code?

    • A. Exactly ten times
    • B. While the condition is True
    • C. While the condition is False
    • D. Until the user presses Enter

  2. 2. What is the technical term for a loop that repeats an unknown number of times?

    • A. Definite iteration
    • B. Indefinite iteration
    • C. Selection
    • D. Variable assignment

  3. 3. What happens if the condition in a while loop never becomes False?

    • A. The program crashes immediately
    • B. An infinite loop occurs
    • C. The loop runs once and stops
    • D. Python automatically fixes the error

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