Science lesson plan · 9th grade (Year 10 in England) · 45 minutes
Rates of reaction
Chemical reactions, acids and bases
CCSS NGSS.HS-PS1-5England: KS4 Combined Science: The rate and extent of chemical change
Objective and success criteria
Students will: Rates of reaction.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Exothermic and endothermic reactions
Leads to: Calculate mean rates of reaction from data; Predict how an equilibrium shifts (Le Chatelier)
Materials: Teacher demo or video, Indicator color chart, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Exothermic and endothermic reactions). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Is this exothermic or endothermic: photosynthesis? (exothermic / endothermic) → endothermicPrompt: Does it give out heat or take heat in?
- The temperature of a reaction mixture changes from 18 °C to 43 °C. What is the temperature change? (Use a minus sign for a fall.) → 25 °CPrompt: Change = final temperature − starting temperature.
- In an exothermic reaction, the energy of the products is… (exactly the same as the reactants / lower than the energy of the reactants / zero / higher than the energy of the reactants) → lower than the energy of the reactantsPrompt: Energy has been given out to the surroundings.
Hook · 5 min
- Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
- Share the objective: Rates of reaction. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: A reaction produces 150 cm³ of gas in 50 seconds. What is the mean rate of reaction, in cm³/s?
- Step 1: 150 ÷ 50 = 3
- Step 2: So the answer is: 3 cm³/s
- Answer: 3 cm³/s
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- A reaction produces 15 cm³ of gas in 10 seconds. What is the mean rate of reaction, in cm³/s? → 1.5 cm³/sPrompt: mean rate = amount of product ÷ time
- Why does a more concentrated acid react faster? (It is hotter / The particles are heavier / It has a lower pH so no collisions are needed / There are more acid particles in the same volume, so collisions are more frequent) → There are more acid particles in the same volume, so collisions are more frequentPrompt: Concentration is how crowded the particles are.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Rates of reaction: which statement is NOT true? (Increasing surface area increases the rate. / A catalyst is not used up in a reaction. / Lower temperatures make reactions faster. / Food lasts longer in a fridge because reactions are slower at low temperature.) → Lower temperatures make reactions faster.Prompt: What does a catalyst change, and what does it not change?
- A reaction produces 20 cm³ of gas in 20 seconds. What is the mean rate of reaction, in cm³/s? → 1 cm³/sPrompt: mean rate = amount of product ÷ time
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Exothermic and endothermic reactions.
- Use concrete materials: teacher demo or video.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Calculate mean rates of reaction from data; Predict how an equilibrium shifts (Le Chatelier).
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.
Free lesson plan from eurekami.com/lesson-plan-builder