Lesson Plan

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Lesson Plan
Grade: Date: 01/12/2025
Subject: Physics
Lesson Topic: use the unified atomic mass unit (u) as a unit of mass
Learning Objective/s:
  • Describe the definition of the unified atomic mass unit and its relationship to carbon‑12.
  • Convert masses between unified atomic mass units and kilograms.
  • Apply the u‑to‑kg conversion to calculate nuclear masses and Q‑values in radiation problems.
  • Use E = mc² to relate mass in u to energy in MeV.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Scientific calculators
  • Worksheet with conversion tables and practice problems
  • Periodic‑table handout
  • Answer key for teacher reference
 Introduction:
Begin with a quick question: “If a single atom weighs 10⁻²⁷ kg, how could we conveniently express its mass?” Connect this to prior work on atomic structure and explain that today students will master the unified atomic mass unit as a practical mass unit. Success criteria: students will accurately convert between u and kg and apply the conversion in simple nuclear calculations.
Lesson Structure:
  1. Do‑now (5 min): Estimate a mass given in kg and write it in u on a short worksheet.
  2. Direct instruction (10 min): Define u, present the exact value in kg, and discuss why it is useful (slides).
  3. Guided practice (12 min): Convert carbon‑12 and uranium‑235 masses together; use clicker questions for immediate feedback.
  4. Application activity (15 min): Small groups calculate the Q‑value for the α‑decay of ²³⁸U using provided mass data; groups share results.
  5. Independent practice (10 min): Students complete two practice problems (mass of ⁵⁶Fe nucleus, beta‑particle mass) on the worksheet.
  6. Summary & check (5 min): Review key formulas; students write the u‑to‑kg conversion formula on an exit ticket.
Conclusion:
Recap the definition of the unified atomic mass unit and the conversion factor to kilograms, emphasizing its role in nuclear calculations. For the exit ticket, students write the conversion formula from u to kg from memory. Homework: complete the remaining practice questions in the worksheet and bring any uncertainties to the next class.