Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Chemistry
Curriculum Theme: Chemistry
Previous Lesson: Standard Separation Techniques.
Topic: PARTICULAR NATURE OF MATTER
Subject Matter: Physical and chemical changes with examples, atoms and molecules, Dalton’s atomic theory

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Differentiate between physical and chemical changes with examples.
Summarize the key points of Dalton’s atomic theory.

Affective Domain:

Appreciate the importance of understanding changes in matter.
Develop an interest in the particulate nature of matter.

Psychomotor Domain:

Use models to represent atoms and molecules.
Observe and record changes during practical demonstrations.

Participate actively in class discussions.
Collaborate in practical activities.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum
State Unified Scheme of Work
New School Chemistry for Senior Secondary Schools by Osei Yaw Ababio

Instructional Materials

The teacher will teach this lesson with the aid of:

Water
Common salt
Sugar
Candle
Matches
Magnesium ribbon
Starch
Pap (akamu)
Calcium trioxocarbonate (iv) (CaCO3) (chalk powder)
Models (coloured beads or plasticine) to represent atoms and molecules

Rationale for the Lesson

This lesson helps pupils understand how matter changes around them in everyday life, both physically and chemically. It also introduces them to the fundamental building blocks of matter, which is important for understanding all chemical reactions.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of states of matter and simple mixtures.

Lesson Content/Board Summary

PARTICULAR NATURE OF MATTER

1. Physical Changes

A physical change is a change in the physical properties of a substance without forming a new substance. The chemical composition of the substance remains the same.

The following are characteristics of physical changes:

No new substance is formed.
The change is usually reversible.
Little or no energy is absorbed or released.
The chemical composition remains unchanged.

The following are examples of physical changes:

Melting of ice.
Dissolving of salt or sugar in water.
Boiling of water.
Magnetisation of iron.
Condensation of steam.

2. Chemical Changes

A chemical change is a change in which a new substance with different chemical properties is formed. The chemical composition of the original substance is altered.

The following are characteristics of chemical changes:

New substances are formed.
The change is usually irreversible.
A significant amount of energy (heat, light, sound) is often absorbed or released.
The chemical composition changes.

The following are examples of chemical changes:

Burning of wood or paper.
Rusting of iron.
Digestion of food.
Preparation of pap (akamu) from corn.
Burning of magnesium ribbon.
Making of chalk (calcium trioxocarbonate(IV)) from limestone components.

3. Atoms and Molecules

An **atom** is the smallest particle of an element that can take part in a chemical reaction. It retains the chemical identity of the element.

A **molecule** is a group of two or more atoms held together by chemical bonds. Molecules can be made of atoms of the same element (e.g., O₂, N₂) or different elements (e.g., H₂O, CO₂).

Atoms and molecules can be represented using models, where different colours or sizes of beads represent different types of atoms.

4. Dalton’s Atomic Theory

John Dalton proposed his atomic theory in 1808. The main postulates of his theory are:

All matter is made up of tiny, indivisible particles called atoms.
Atoms of the same element are identical in mass, size, and chemical properties.
Atoms of different elements are different in mass, size, and chemical properties.
Atoms cannot be created, destroyed, or subdivided in a chemical reaction.
Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
In chemical reactions, atoms are rearranged, separated, or combined.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction/Review
Teacher’s Activity: The teacher reviews the previous lesson by asking questions related to states of matter. The teacher then introduces the topic “Particular Nature of Matter” by asking pupils to observe common changes around them, like water boiling or wood burning.
Pupils’ Activity: Pupils answer questions and pay attention to the introduction.
Learning Point: Pupils recall previous knowledge and are introduced to the new topic.

Step 2: Physical Changes

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher demonstrates physical changes by:

Dissolving common salt/sugar in water.
Melting a piece of candle wax (without burning the wick).

The teacher explains the concept of physical change, its characteristics, and gives more examples.
Pupils’ Activity: Pupils observe the demonstrations, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and characteristics of physical changes.

Step 3: Chemical Changes

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher demonstrates chemical changes by:

Burning the wick of a candle (showing light and heat).
Burning a piece of magnesium ribbon.
Guiding pupils to observe the preparation of pap (akamu) or explaining how starch changes during cooking.
Guiding pupils to make chalk (CaCO3) from relevant components if materials are available, or explaining the process as a chemical change.

The teacher explains the concept of chemical change, its characteristics, and gives more examples.
Pupils’ Activity: Pupils observe the demonstrations, participate in guided activities, take notes, and ask questions.
Learning Point: Pupils understand the definition and characteristics of chemical changes.

Step 4: Atoms and Molecules

Time: 5 minutes
Teaching Skill: Explanation/Visualisation
Teacher’s Activity: The teacher explains the definitions of atoms and molecules. The teacher uses models (coloured beads) to represent atoms of different elements and how they combine to form molecules (e.g., H₂, O₂, H₂O, CO₂).
Pupils’ Activity: Pupils observe the models, listen to explanations, and practice representing simple atoms and molecules with their own models if available.
Learning Point: Pupils understand the basic concepts of atoms and molecules and how they are represented.

Step 5: Dalton’s Atomic Theory

Time: 5 minutes
Teaching Skill: Lecture/Explanation
Teacher’s Activity: The teacher clearly states and explains the main postulates of Dalton’s Atomic Theory.
Pupils’ Activity: Pupils listen attentively, take notes, and ask questions for better understanding.
Learning Point: Pupils learn the fundamental principles of Dalton’s Atomic Theory.

Step 6: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define physical change and give two examples.
State two differences between physical and chemical changes.
What is an atom?
Mention any three postulates of Dalton’s Atomic Theory.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 7: Conclusion

Time: 5 minutes
Teaching Skill: Summarization/Assignment
Teacher’s Activity: The teacher briefly summarizes the key points of the lesson, emphasizing the difference between physical and chemical changes, and the importance of atoms and molecules. The teacher then assigns homework.
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their learning and receive further practice.

Lesson Keywords

Physical change – A change in the physical properties of a substance without forming a new substance.
Chemical change – A change where a new substance with different chemical properties is formed.
Atom – The smallest particle of an element that can take part in a chemical reaction.
Molecule – A group of two or more atoms held together by chemical bonds.
Dalton’s Atomic Theory – A scientific theory proposing that all matter is composed of discrete units called atoms.

Differentiation

For pupils who grasp concepts quickly, they can be encouraged to research modern atomic theory and its differences from Dalton’s theory. For those who need more support, the teacher can provide simplified diagrams and additional one-on-one explanations during practical demonstrations.

Note for teachers using this lesson plan

Ensure all demonstration materials are ready before the lesson. Emphasize safety during demonstrations, especially with fire. Encourage pupils to actively participate and ask questions. Use real-life examples to make the concepts relatable.