Lesson T1.2.1

T1.2.1 Sorting algorithms Quiz: KS3 Computing, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T1.2.1, Sorting algorithms: 20 multiple choice questions for the KS3 Computing (National Curriculum), Unit 1: Computational thinking and algorithms, written with Revision Ninja.

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The 20 questions

  1. What is the primary purpose of a sorting algorithm?

    • Searching values
    • Encrypting data
    • Compressing files
    • Ordering items

  2. In bubble sort, where does the largest unsorted value move after one pass?

    • The correct end
    • The exact middle
    • A random position
    • The very start

  3. Which sorting method repeatedly finds the smallest item and moves it to the front?

    • Binary search
    • Linear search
    • Hash table lookup
    • Selection sort

  4. A list has 5 items. On its first pass, how many adjacent pairs does bubble sort compare?

    • 10
    • 4
    • 5
    • 1

  5. The list is [5, 2, 9, 1]. What is the list after one full bubble sort pass?

    • [5, 2, 1, 9]
    • [9, 5, 2, 1]
    • [2, 5, 1, 9]
    • [1, 2, 5, 9]

  6. Why is insertion sort efficient for a nearly sorted list?

    • It requires no memory
    • It skips all checks
    • Few movements needed
    • It uses binary search

  7. Why do programmers compare different sorting algorithms?

    • To test screen resolution
    • To find spelling errors
    • To check file size
    • To measure efficiency

  8. The list is [7, 3, 5]. After the first pass of selection sort, what is the list?

    • [3, 5, 7]
    • [3, 7, 5]
    • [5, 3, 7]
    • [7, 3, 5]

  9. What does arranging items in ascending order mean?

    • Largest to smallest
    • Alphabetical reverse
    • Randomly shuffled
    • Smallest to largest

  10. In a list starting with Zoe then Adam, which pair does bubble sort compare first?

    • First and last
    • Zoe and Adam
    • Adam and Zoe
    • Middle two items

  11. What signals that a bubble sort has finished sorting a list?

    • All items deleted
    • The timer expires
    • Zero swaps made
    • Maximum swaps reached

  12. How does insertion sort construct its final sorted structure?

    • Reversing the list
    • Inserting into order
    • Swapping random pairs
    • Splitting in halves

  13. Why must sorting algorithms compare pairs of items?

    • To compress memory
    • To establish order
    • To count duplicates
    • To delete entries

  14. A list of 4 items is sorted by bubble sort. What is the most passes that are needed?

    • 1
    • 4
    • 6
    • 3

  15. Bubble sort is applied to [3, 1, 2]. How many swaps happen in total?

    • 0
    • 1
    • 3
    • 2

  16. Selection sort is applied to [6, 4, 8, 2]. What is the list after the first pass?

    • [4, 6, 8, 2]
    • [2, 6, 8, 4]
    • [2, 8, 4, 6]
    • [2, 4, 8, 6]

  17. A sort is needed for a list of exam scores from lowest to highest. Which order should be used?

    • Ascending order
    • Random order
    • Descending order
    • Reverse alphabetical order

  18. Why is bubble sort inefficient for very large lists?

    • It deletes data
    • It uses only audio
    • It requires sorting
    • Too many comparisons

  19. Which sort works by repeatedly swapping neighbouring items that are out of order?

    • Selection sort
    • Bubble sort
    • Binary search
    • Linear search

  20. Which of these lists is in ascending order?

    • [5, 8, 1, 3]
    • [1, 3, 5, 8]
    • [8, 5, 3, 1]
    • [3, 1, 8, 5]

All KS3 Computing quizzes