Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: describe an experiment to determine the acceleration of free fall using a falling object
Learning Objective/s:
  • Describe the experimental method for determining g using a falling object.
  • Calculate g from measured distances and times using s = ½gt² and related equations.
  • Analyse data by plotting s against t² and determining the gradient.
  • Evaluate sources of random and systematic error and estimate the uncertainty in g.
  • Communicate findings and compare the experimental value with the accepted value.
Materials Needed:
  • Metal ball or dense sphere (≈2 cm diameter)
  • Retort stand with clamps
  • Electromagnetic release mechanism or simple clamp
  • One or two photogate timers
  • Meter rule or measuring tape
  • Stopwatch (for verification)
  • Data collection sheet
  • Safety goggles (optional)
 Introduction:
Begin with a quick demonstration of a ball dropping and ask students what determines how fast it falls. Recall the kinematic equation s = ½gt² from previous lessons and highlight that today they will obtain g experimentally. Success will be measured by producing a graph of s against t² and calculating g within 5 % of the accepted value.
Lesson Structure:
  1. Do‑now (5') – Students answer a short question on the relationship between distance, time and acceleration.
  2. Mini‑lecture (10') – Review equations of motion, derive g = 2s/t², and explain photogate operation.
  3. Set‑up demonstration (10') – Teacher shows how to assemble the stand, attach the ball and align photogates.
  4. Student lab activity (20') – Groups record s and t for at least five heights, repeat measurements, and complete data sheet.
  5. Data analysis (10') – Plot s versus t², determine gradient, calculate g, and discuss uncertainties.
  6. Whole‑class debrief (5') – Groups share results, compare with the accepted value, and identify error sources.
Conclusion:
Summarise how the linear relationship between s and t² allowed us to extract g and note the typical experimental value obtained. For the exit ticket, each student writes the percentage difference between their calculated g and 9.81 m s⁻². Assign homework to research another method of measuring g and prepare a brief comparison.