Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 1st Term
Week: 9
Age: 15 years
Duration: 45 minutes
Subject: Refrigeration And Air Conditioning
Curriculum Theme: Trade
Previous Lesson: Nature Of Matter: States of Matter and Properties.
Topic: Nature of matter Change of state of matter
Subject Matter: Change of state, melting, freezing, evaporation, condensation

Specific Objectives

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

Cognitive Domain:

Define change of state of matter.
Explain the processes of melting, freezing, evaporation, and condensation.
Identify examples of each change of state.

Affective Domain:

Appreciate the relevance of changes of state in daily life and in refrigeration.
Show interest in observing changes of state.

Psychomotor Domain:

Observe and describe the changes in state using practical examples.
Draw simple diagrams to illustrate changes of state.

Collaborate with peers to discuss examples of changes of state.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (JSS 1-3) and Senior Secondary Education Curriculum for Trade Subjects (SS1-3).
State Unified Scheme of Work for Senior Secondary School 1, Refrigeration and Air Conditioning.
Refrigeration and Air Conditioning for Senior Secondary Schools by [Author’s Name, e.g., A. O. Okoro].

Instructional Materials

The teacher will teach this lesson with the aid of:

An ice block
A kettle with boiling water to produce steam
A container of water
A heat source (e.g., Bunsen burner, hot plate)
A chart showing the three states of matter and the processes of change.
Whiteboard/Chalkboard and markers/chalk.

Rationale for the Lesson

Understanding the changes in the state of matter is important for pupils to grasp how refrigeration and air conditioning systems work. It helps them understand everyday phenomena like ice melting or water boiling, which are fundamental to many industrial and domestic applications.

Prerequisite/Previous Knowledge

Pupils should have prior knowledge of the three states of matter: solid, liquid, and gas.

Lesson Content/Board Summary

Change of State of Matter

Definition of Change of State

Change of state refers to the physical process where matter transitions from one state (solid, liquid, or gas) to another due to changes in temperature or pressure.

Types of Change of State

The following are common types of change of state:

Melting
Freezing
Evaporation
Condensation

Melting

Melting is the process by which a solid changes into a liquid when heated. The temperature at which a solid melts is called its melting point.

Example: An ice block changing into water when exposed to heat.

Freezing

Freezing is the process by which a liquid changes into a solid when cooled. The temperature at which a liquid freezes is called its freezing point.

Example: Water changing into ice when placed in a freezer.

Evaporation

Evaporation is the process by which a liquid changes into a gas (vapour) without boiling, usually occurring at the surface of the liquid. It happens at temperatures below the boiling point.

Example: Wet clothes drying in the sun, water turning into steam from a kettle.

Condensation

Condensation is the process by which a gas (vapour) changes into a liquid when cooled. It is the reverse process of evaporation.

Example: Water droplets forming on a cold glass of drink or on the lid of a pot of boiling water.

Teaching Methods/Instructional Techniques

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

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to recall the three states of matter they learned in previous classes. The teacher then introduces the topic by asking pupils what happens to ice when left outside or to water when boiled.
Pupils’ Activity: Pupils respond to the questions and share their previous knowledge of states of matter.
Learning Point: Pupils recall prior knowledge and are prepared for the new topic.

Step 2: Explanation of Change of State

Time: 8 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines change of state, explaining that matter can move between solid, liquid, and gas forms. The teacher then uses the chart to illustrate the transitions between these states.
Pupils’ Activity: Pupils listen attentively, observe the chart, and ask questions for clarity.
Learning Point: Pupils understand the general concept of change of state.

Step 3: Melting and Freezing

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher demonstrates melting by placing an ice block in a container and allowing it to change into water. The teacher explains that this process is called melting. The teacher then explains freezing as the reverse process where liquid turns to solid when cooled.
Pupils’ Activity: Pupils observe the melting ice and listen to the explanations. They may give examples of freezing from their experience.
Learning Point: Pupils understand melting and freezing with practical examples.

Step 4: Evaporation

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher places some water in a kettle on a heat source to produce steam. The teacher explains that the water changing into steam (a gas) is called evaporation, and that it can also occur at lower temperatures (e.g., drying clothes).
Pupils’ Activity: Pupils observe the steam from the kettle and listen to the explanation. They may share examples of evaporation they have seen.
Learning Point: Pupils understand the concept of evaporation and its examples.

Step 5: Condensation

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: Using the steam from the kettle, the teacher holds a cold surface (e.g., a cold metal plate or glass) above the steam to show water droplets forming. The teacher explains that this process, where gas turns back into liquid, is called condensation.
Pupils’ Activity: Pupils observe the formation of water droplets and listen to the explanation. They may identify other instances of condensation.
Learning Point: Pupils understand condensation as the reverse of evaporation.

Step 6: Class Discussion/Examples

Time: 3 minutes
Teaching Skill: Question and Answer
Teacher’s Activity: The teacher asks pupils to give more examples of melting, freezing, evaporation, and condensation from their daily experiences.
Pupils’ Activity: Pupils actively participate, sharing various examples of changes of state.
Learning Point: Pupils reinforce their understanding by relating the concepts to real-life situations.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

Define change of state of matter.
Explain what happens during melting and freezing.
Distinguish between evaporation and condensation.
Mention two examples of evaporation.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definitions and examples of the changes of state. The teacher assigns homework: “Draw and label a diagram showing the three states of matter and the processes of change between them.”
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils consolidate their learning and have an assignment to reinforce the lesson.

Lesson Keywords

Change of State – The physical process where matter transforms from one state (solid, liquid, gas) to another.
Melting – The process of a solid changing into a liquid when heated.
Freezing – The process of a liquid changing into a solid when cooled.
Evaporation – The process of a liquid changing into a gas (vapour) below its boiling point.
Condensation – The process of a gas (vapour) changing into a liquid when cooled.

Differentiation

The teacher will provide additional support to pupils who are struggling by using simplified language and more direct examples. Advanced learners will be encouraged to research and explain practical applications of these changes of state in refrigeration and air conditioning systems.

Note for teachers using this lesson plan

Teachers should adapt the demonstrations to their available resources while ensuring safety. Encourage active participation and real-life examples to make the lesson more engaging and relatable for the pupils.