Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Physics
Lesson Topic: Describe, qualitatively, how the pressure beneath the surface of a liquid changes with depth and density of the liquid
Learning Objective/s:
  • Describe how pressure in a liquid varies with depth.
  • Explain the influence of liquid density on pressure increase.
  • Apply the equation ΔP = ρ g h to calculate pressure changes.
  • Compare pressure at a given depth in liquids of different densities.
  • Identify the role of atmospheric pressure as a constant offset.
Materials Needed:
  • Projector or interactive whiteboard
  • Slides/PowerPoint on pressure concepts
  • Worksheet with pressure calculations
  • Transparent containers with water and oil for demonstration
  • Ruler or measuring tape
  • Calculator (optional)
 Introduction:
Begin with a quick demonstration: press a finger into a bottle of water and ask students what they feel. Recall that pressure is force per unit area and that atmospheric pressure acts on all surfaces. Today we will explore how depth and density change the pressure beneath a liquid surface, and we will predict it using ΔP = ρ g h.
Lesson Structure:
  1. Do‑now (5') – short questions on pressure definition and Pascal’s principle (worksheet).
  2. Mini‑lecture (10') – present ΔP = ρ g h, explain each variable with slides.
  3. Demonstration (8') – compare water and oil columns, measure depth, discuss observed differences.
  4. Guided practice (12') – pairs calculate pressure increase at various depths for water and oil; teacher circulates.
  5. Concept check (5') – quick quiz (clickers or show of hands) on how density affects pressure.
  6. Summary discussion (5') – students summarise key qualitative relationships on the board.
Conclusion:
Review that pressure grows linearly with depth and is larger in denser liquids, while atmospheric pressure adds a constant base. For the exit ticket, each student writes one real‑world example where depth or density matters. Homework: complete the worksheet problems calculating pressure at different depths.