Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Additional Mathematics
Lesson Topic: Use the formulas for the nth term and for the sum of the first n terms to solve problems involving arithmetic or geometric progressions
Learning Objective/s:
  • Describe the characteristics of arithmetic and geometric progressions.
  • Apply nth‑term formulas to find specific terms in AP and GP.
  • Compute the sum of the first n terms and, when applicable, the sum to infinity.
  • Solve multi‑step series problems by selecting appropriate formulas and checking results.
Materials Needed:
  • Projector or interactive whiteboard
  • Printed worksheet with practice questions
  • Calculator (or calculator app)
  • Prepared example slides (AP & GP formulas)
  • Whiteboard markers and eraser
 Introduction:
Begin with a quick real‑world hook, such as budgeting monthly savings, to illustrate why sums of sequences matter. Review that students already know how to identify arithmetic and geometric patterns from previous lessons. State that today they will master using nth‑term and sum formulas to solve series problems, and that success will be demonstrated through guided examples and independent practice.
Lesson Structure:
  1. Do‑now (5'): Identify whether short given sequences are AP or GP.
  2. Mini‑lecture (10'): Review definitions and present nth‑term formulas for AP and GP using projected slides.
  3. Guided AP example (10'): Find the 12th term and sum of the first 12 terms, checking each step together.
  4. Guided GP example (10'): Find the 5th term and sum of the first 5 terms, highlighting differences from AP.
  5. Collaborative practice (15'): Pairs solve the five practice questions, teacher circulates with a step‑by‑step checklist.
  6. Whole‑class debrief (5'): Pairs share solutions; address common mistakes.
  7. Exit ticket (5'): Each student writes the key steps to solve a series problem on a sticky note.
Conclusion:
Summarise the four‑step approach: identify the progression, extract parameters, apply the correct formulas, and verify the answer. Collect exit tickets as a quick check of understanding. Assign homework: complete a worksheet with additional AP and GP problems, including one sum‑to‑infinity question.