Intro to Chemical Reactions
This lesson introduces Year 8 students to the fundamental concepts of chemical reactions. It covers how to identify reactions, the difference between physical and chemical changes, how to write word equations, and the Law of Conservation of Mass.
Learning objectives
- Identify the signs that a chemical reaction has taken place.
- Distinguish between reactants and products in a chemical equation.
- Explain the Law of Conservation of Mass in the context of chemical reactions.
- Compare and contrast chemical reactions with physical changes.
Lesson plan (60 minutes)
Introduction · 5 min
Do Now: List three things you see when a firework goes off. Discuss if these could be signs of a chemical change.
Teaching · 10 min
Teacher Explainer: Using the provided 6-step script to define chemical reactions and identify signs.
Demonstration · 10 min
Demonstration: Mixing vinegar and bicarbonate of soda. Students observe and identify reactants, products, and signs of reaction.
Main Activity · 20 min
Differentiated Worksheet Activity: Students work through Support, Core, or Stretch tasks based on prior attainment.
Assessment · 5 min
Peer Marking: Use the answer key to check worksheet answers.
Conclusion · 10 min
Plenary Quiz: 8-question multiple choice quiz to check understanding.
Key vocabulary
- Reactants
- The starting substances in a chemical reaction.
- Products
- The new substances formed during a chemical reaction.
- Exothermic
- A reaction that releases energy (usually heat) to the surroundings.
- Endothermic
- A reaction that absorbs energy from the surroundings, feeling cold.
- Precipitate
- A solid that forms when two liquids react together.
Core worksheet (first questions)
- Describe the difference between a chemical reaction and a physical change.
- What is the Law of Conservation of Mass?
- Name three pieces of evidence that show a chemical reaction has occurred.
- Write the word equation for: Methane reacts with Oxygen to produce Carbon Dioxide and Water.
Quiz (sample)
1. What is the best definition of a chemical reaction?
- A. A process where substances change state
- B. A process where new substances are formed
- C. A process that can always be easily reversed
- D. A process involving only mixing substances
2. What do we call the starting substances in a chemical reaction?
- A. Products
- B. Chemicals
- C. Reactants
- D. Ingredients
3. Which of these is NOT a sign of a chemical reaction?
- A. Melting ice
- B. Burning wood
- C. Baking a cake
- D. Iron rusting
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