Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Chemistry
Lesson Topic: State that a catalyst decreases the activation energy, $E_a$, of a reaction
Learning Objective/s:
  • State that a catalyst lowers the activation energy ($E_a$) of a reaction.
  • Explain how a lower $E_a$ increases the fraction of molecules that can react and raises the rate constant $k$.
  • Compare reaction rates and activation energies with and without a catalyst using quantitative examples.
  • Interpret potential‑energy diagrams to identify the effect of a catalyst.
  • Relate the unchanged $\Delta H$ to the role of catalysts in reaction pathways.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed handout with potential‑energy diagram
  • Data table of reactions with/without catalyst
  • Scientific calculators
  • Clicker/online response system
 Introduction:
Begin with a quick demonstration of a kitchen catalyst (e.g., yeast in dough) to spark curiosity. Review students’ prior knowledge of activation energy and the Arrhenius equation. Explain that by the end of the lesson they will be able to state how a catalyst changes $E_a$ and predict its effect on reaction rate.
Lesson Structure:
  1. Do‑now (5') – short quiz on the definition of activation energy.
  2. Mini‑lecture (10') – revisit the Arrhenius equation and introduce the catalyst concept.
  3. Diagram analysis (8') – students examine a potential‑energy profile, label the original and lowered $E_a$, and discuss the visual impact.
  4. Data investigation (12') – groups compare the table of reactions, calculate the factor increase in rate, and relate it to the change in $E_a$.
  5. Concept check (5') – clicker questions to confirm understanding of how $E_a$, $k$, and rate are linked.
  6. Summary discussion (5') – teacher synthesises key points and answers lingering questions.
Conclusion:
Recap that a catalyst provides an alternative pathway with a lower $E_a$, increasing the fraction of reactive molecules and the rate constant while leaving $\Delta H$ unchanged. Collect an exit ticket asking students to write one sentence describing this effect. For homework, assign problems that require calculating the change in rate constant when $E_a$ is reduced by a given amount.