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Year 10 Computer Science: Sorting algorithms lesson pack

A complete, ready-to-teach GCSE lesson on sorting algorithms. 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

Sorting Algorithms: Bubble and Merge Sort

This lesson introduces Year 10 students to the fundamental sorting algorithms required for GCSE Computer Science: Bubble Sort and Merge Sort. Students will learn the mechanics of each algorithm, how to trace them manually, and the basic differences in their efficiency.

Learning objectives

  • Explain the steps involved in the Bubble Sort and Merge Sort algorithms.
  • Trace the execution of a sorting algorithm using a given set of data.
  • Compare the efficiency of Bubble Sort and Merge Sort in terms of time and space.

Lesson plan (60 minutes)

  1. Introduction · 5 min

    Do Now: Students are given a scrambled list of 5 numbers on the board and asked to write down the steps they would take to sort them manually.

  2. Direct Instruction · 15 min

    Teacher-led explanation of Bubble Sort and Merge Sort using the 'Explainer' script and worked example.

  3. Guided Practice · 10 min

    Live demonstration: Using 6 students at the front of the class to act out a Bubble Sort.

  4. Independent Practice · 20 min

    Differentiated worksheets: Students work through Support, Core, or Stretch tasks based on prior attainment.

  5. Plenary/Review · 10 min

    Multiple-choice quiz to check for understanding and address misconceptions.

Key vocabulary

Algorithm
A step-by-step set of instructions to solve a problem.
Bubble Sort
A sorting method that swaps adjacent elements if they are in the wrong order.
Merge Sort
A fast sorting method that splits a list into smaller sub-lists and then joins them back together.
Comparison
Checking two values to see which is larger or smaller.
Divide and Conquer
An algorithmic pattern that breaks a problem into smaller sub-problems.

Core worksheet (first questions)

  1. Describe how a Bubble Sort algorithm works in your own words.
  2. Show the state of the list [8, 3, 5, 1] after every swap in the first pass of a Bubble Sort.
  3. What does the term 'Divide and Conquer' mean in the context of Merge Sort?
  4. Compare the efficiency of Bubble Sort and Merge Sort. Which one scales better?

Quiz (sample)

  1. 1. How does a Bubble Sort work?

    • A. It splits the list into two halves repeatedly.
    • B. It compares adjacent items and swaps them if they are in the wrong order.
    • C. It picks a random number and moves it to the start.
    • D. It finds the smallest number and puts it at the end.

  2. 2. Which strategy does Merge Sort use?

    • A. Search and Destroy
    • B. Divide and Conquer
    • C. Split and Sort
    • D. Binary Logic

  3. 3. What is used in Bubble Sort to determine if the list is finished?

    • A. A timer
    • B. A counter that reaches 100
    • C. A flag variable (e.g., swapped = True)
    • D. It stops automatically after one pass

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Support and Stretch worksheets, every answer and model answer, the teaching explainer and common misconceptions, editable and ready to print as PDF or Word.

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