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Coding · Grade 9

Algorithms and Problem Decomposition

High-school learners define algorithms precisely (finite, definite, effective, with input and output) and test procedures against that definition, including the unsolved Collatz problem as a case where testing is not proof. They represent algorithms as flowcharts and pseudocode, trace classic algorithms such as Euclid's GCD with trace tables, and decompose problems while comparing algorithms for correctness and efficiency.

  • 4 lessons
  • About 85 minutes
  • Check what you learned: 8 questions
  • Ways to answer: choose an answer, put code in order, trace code, match pairs, type a number and sort into groups
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What learners will discover

  • State the properties of an algorithm and judge whether a procedure is an algorithm.
  • Represent algorithms with flowcharts and pseudocode using sequence, selection and iteration.
  • Trace algorithms with loops and conditions using trace tables to predict their output.
  • Decompose a problem and compare algorithms for correctness and efficiency.

Lessons

  1. What counts as an algorithm? 6 steps3 practiceabout 20 min
  2. Flowcharts and pseudocode 5 steps3 practiceabout 20 min
  3. Trace tables 5 steps3 practiceabout 22 min
  4. Decomposing and comparing algorithms 5 steps4 practiceabout 18 min
  5. Check what you learned 8 questions at the end

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