Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Additional Mathematics
Lesson Topic: Recognise the difference between permutations and combinations and know when each should be used
Learning Objective/s:
  • Describe the difference between permutations and combinations and identify when order matters.
  • Apply the permutation formula P(n,r) to solve arrangement problems.
  • Apply the combination formula C(n,r) to solve selection problems.
  • Analyse word problems to decide whether to use permutations or combinations and avoid common errors.
Materials Needed:
  • Projector or interactive whiteboard
  • Printed worksheet with practice questions
  • Calculator or computer algebra system
  • Set of index cards for hands‑on arranging/choosing activity
  • Whiteboard markers and eraser
 Introduction:
Begin with a quick mental puzzle: how many different 4‑letter passwords can be formed from the 26‑letter alphabet? Recall that order matters in arrangements but not in selections, linking to prior work on factorials. Students will know they can decide which formula to use and will be able to state the success criteria: correctly identify and solve permutation and combination problems.
Lesson Structure:
  1. Do‑now (5'): Students answer the password question individually and write their answer; teacher checks for understanding.
  2. Mini‑lecture (10'): Define permutations vs. combinations, present formulas, and illustrate with the summary table.
  3. Guided practice – Permutation (12'): Work through the password example together, students fill in each step on the board.
  4. Guided practice – Combination (12'): Solve the committee selection example, discussing why order does not matter.
  5. Independent practice (15'): Worksheet with four mixed problems; teacher circulates, prompting reasoning.
  6. Check for understanding (6'): Exit ticket – one problem where students state which method to use and give the answer.
Conclusion:
Recap the key distinctions and formulas for permutations and combinations, emphasizing the “order matters vs. does not matter” cue. Collect exit tickets to gauge immediate mastery and assign homework: complete an additional set of five mixed problems from the textbook to reinforce the concepts.