Week Eight
Subject: Basic Science
Week of Third Term: 8th Term
Class: Primary Five
Topic: Acids and Bases
Subtopic: Physical Properties of Acids and Bases Using Litmus Paper
Objectives
At the end of the lesson, pupils should be able to:
- List the physical properties of acids and bases.
- Demonstrate the effect of acids and bases on red and blue litmus paper.
- Identify substances as acidic or basic based on litmus paper tests.
Entry Behaviour
Pupils should already be familiar with common household substances such as lemon juice, vinegar, and soap, and know their uses.
Instructional Materials
- Red and blue litmus papers.
- Sample substances: lemon juice, vinegar, baking soda solution, wood ash solution, and soap.
- Charts showing examples of acids and bases.
Reference Materials
- Ijiyemi, C. (2016). Foundations of Science and Technology for Primary School Book 5. Lagos: Metropolitan Publishers.
- Oyinlola, M., Rahaman, B., & Ezeume, I. (2015). Basic Science and Technology for Primary School Book 5 (BEC Edition). Lagos: Spectrum Book Limited.
Content
Physical Properties of Acids:
- Sour taste.
- Turns blue litmus paper red.
- Can be corrosive in concentrated forms.
Physical Properties of Bases:
- Bitter taste.
- Slippery feel.
- Turns red litmus paper blue.
Using Litmus Paper:
- Acids react with blue litmus paper and change its color to red.
- Bases react with red litmus paper and change its color to blue.
Lesson Presentation
Step 1: Introduction
Start by asking pupils if they’ve tasted lemon juice or touched soap. Ask: What do they feel like? Relate their responses to acids and bases.
Step 2: Explanation
Explain the physical properties of acids and bases using simple terms and examples like lemon juice and wood ash.
Step 3: Demonstration
- Dip blue litmus paper into lemon juice and observe the color change to red.
- Dip red litmus paper into a baking soda solution and observe the color change to blue.
Step 4: Guided Practice
Divide pupils into groups. Provide substances like vinegar, soap, and wood ash solution. Guide them to test each with litmus paper and record their findings.
Step 5: Independent Practice
Provide pupils with additional substances (e.g., orange juice, saltwater). Let them test and classify these independently as acidic or basic using litmus paper.
Step 6: Feedback
Review the pupils’ results and clarify any misconceptions about acidity and basicity.
Evaluation
Formative Assessment:
- What color does blue litmus paper turn in an acid?
- Name one property of a base.
Summative Assessment:
- List two physical properties of acids.
- Explain what happens when red litmus paper is dipped into a basic solution.
- Name two substances that can be tested as acidic or basic.
Summary/Conclusion
Summarize the physical properties of acids and bases and the role of litmus paper in identifying them. Highlight the importance of identifying acids and bases for safety and daily use.
Assignment
At home, find one acidic substance and one basic substance. Write down their names and describe what you think their effect on litmus paper would be.