Rates of Reaction

Overview

This 60-minute lesson introduces Year 11 students to the factors affecting the rates of chemical reactions. It aligns with the New Zealand Curriculum Refresh, specifically focusing on Understanding about Science strand (Nature of Science), and key competencies including thinking and using language, symbols and text. The lesson incorporates practical experiments, conceptual understanding, and caters to diverse learning needs.

Learning Objectives

By the end of this lesson, students will be able to:

Explain what is meant by the rate of a chemical reaction.
Identify and describe the four main factors that affect reaction rates: concentration, temperature, surface area, and catalysts.
Predict how changes in these factors affect the speed of a reaction.
Demonstrate understanding through participating in a practical experiment measuring one factor’s effect on reaction rate.

This lesson addresses the New Zealand Curriculum level 5 (Year 11) Science Achievement Objectives:

Nature of Science - Understandings: The rate of chemical reactions can be affected by changes in conditions[AC9S5U01].
Nature of Science - Investigating in Science: Plan and conduct a controlled experiment to investigate a factor affecting reaction rate[AC9S5I01].
Key Competencies: Thinking; Using language, symbols, and texts; Managing self.

Success Criteria

Students will demonstrate success if they can:

Clearly explain the meaning of reaction rate in their own words.
Describe how each factor (concentration, temperature, surface area, catalyst) influences the speed of reactions.
Accurately conduct a simple experiment measuring reaction rate.
Record observations clearly and draw conclusions supported by evidence.
Articulate safety precautions and scientific reasoning behind their experimental choices.

Resources Needed

Hydrochloric acid solution (diluted)
Marble chips (Calcium carbonate)
Thermometer
Stopwatch or timer
Different sizes of marble chips (for surface area variation)
Beakers and test tubes
Safety goggles and gloves
Whiteboards and markers for group work
Dyslexia-friendly summary sheets using a clear font and high contrast colours

Lesson Structure

1. Introduction & Engagement (10 minutes)

Begin with a brief discussion: What is a chemical reaction? What does “rate of reaction” mean?
Use an everyday example: Making a cup of tea — how fast it brews changes with temperature and stirring.
Present the four factors influencing reaction rates: concentration, temperature, surface area, and catalysts.
Write the terms on the board visually with images to support dyslexic learners.

2. Demonstration & Explanation (10 minutes)

Demonstrate a simple reaction: Marble chips + dilute hydrochloric acid.
Show how changing one factor affects the reaction speed (e.g., using finer marble chips for increased surface area).
Use a graphical diagram on the board showing how reaction rate changes.
Check understanding with formative questioning: How does particle size affect the number of collisions?

3. Practical Investigation (30 minutes)

Students work in groups of 5 to conduct an experiment investigating the effect of surface area on reaction rate.
Procedure:
Measure a fixed volume and concentration of acid.
Use different sizes of marble chips (large vs powder).
Measure time taken for reaction to complete or volume of gas produced in a fixed time.
Students record results in a structured table.
Support students with written procedure sheets designed with dyslexia-friendly fonts and layouts.
Monitor groups, provide scaffolded questions for groups needing more guidance.

4. Conclusion & Assessment (10 minutes)

Groups share their results and discuss.
Teacher consolidates key points linking experiment findings to theory.
Summative assessment: Short quiz or exit slip that asks students to explain how one factor affects reaction rate and why.
Self-assessment: Checklist for students to rate their understanding against the learning objectives.

Differentiation Strategies

For diverse learners:
Provide step-by-step visual instructions and written summaries.
Use peer support and mixed-ability groupings.
Allow oral responses or diagrams instead of written answers where appropriate.
Dyslexia-friendly materials: Use fonts like Arial or Comic Sans, larger text, coloured overlays, and bullet points.
Extra time for processing information during assessments.
For advanced learners:
Challenge with calculating reaction rates from data (rate = amount / time).
Introduce the concept of activation energy and discuss catalysts in more detail.
Extension task: Design an experiment to test the effect of temperature or concentration with predicted hypotheses.

Extension Activities

Investigate catalysts in everyday life and industry (e.g., catalytic converters in cars).
Research and present a report on how enzymes work as biological catalysts.
Create a digital or physical infographic explaining factors affecting reaction rate with real-life applications.

Safety Considerations

Wear safety goggles and gloves at all times during experiments.
Handle hydrochloric acid with care; use diluted solutions.
Be aware of safe disposal methods for acid and marble chips.
Ensure students wash hands thoroughly after practical work.

This lesson plan integrates practical inquiry, conceptual understanding, and inclusive pedagogy appropriate for Year 11 students following the New Zealand Curriculum Refresh. The multi-modal approach ensures engagement, clarity, and opportunities for all learners to succeed.

Teaching Instructions