Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: Second Term
Week: 1
Age: 15 years
Duration: 45 minutes
Subject: Refrigeration And Air Conditioning
Curriculum Theme: Trade
Previous Lesson: .
Topic: Pressure and its Measurement
Subject Matter: Concept of pressure, pressure units, examples of pressure

Specific Objectives

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

Cognitive Domain:

Define pressure.
State the formula for calculating pressure.
List common units of pressure.
Identify examples of pressure in everyday life.

Affective Domain:

Appreciate the importance of understanding pressure in refrigeration and air conditioning.
Show interest in learning about different pressure units.

Psychomotor Domain:

Identify a pressure gauge.
Relate the concept of pressure to practical demonstrations.

Participate actively in class discussions regarding pressure.

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.
State Unified Scheme of Work for Senior Secondary School 1, Refrigeration And Air Conditioning.
Refrigeration and Air Conditioning Technology by William C. Whitman, Bill Johnson, John Tomczyk.
https://www.engineeringtoolbox.com/pressure-units-d_577.html
https://byjus.com/physics/pressure/

Instructional Materials

The teacher will teach this lesson with the aid of:

Pressure gauge
Balloon
Air pump
Sealed bottle
Whiteboard/blackboard and markers/chalk
Charts showing pressure units and examples

Rationale for the Lesson

Understanding pressure is important for pupils as it is a fundamental concept in refrigeration and air conditioning systems. This lesson helps pupils grasp how pressure affects the operation of these systems and its applications in daily life.

Prerequisite/Previous Knowledge

Pupils have a basic understanding of force and area from their previous science classes.

Lesson Content/Board Summary

Pressure and its Measurement

Concept of Pressure

Pressure is defined as the force applied perpendicular to the surface of an object per unit area over which the force is distributed.

The formula for pressure is:

Pressure (P) = Force (F) / Area (A)

Where:

Force is measured in Newtons (N).
Area is measured in square meters (m²).

Units of Pressure

The standard SI unit for pressure is the Pascal (Pa), which is equivalent to one Newton per square meter (N/m²).

Other common units of pressure include:

Pounds per square inch (PSI or lb/in²)
Bar
Atmosphere (atm)
Millimeters of mercury (mmHg)
Kilopascals (kPa)

Examples of Pressure in Daily Life

Pressure is encountered in many aspects of daily life and in various technologies:

Inflating a bicycle tire with an air pump.
The pressure of water in pipes.
Atmospheric pressure exerted by the air around us.
Cutting with a sharp knife (small area, high pressure).
Walking on snow with snowshoes (large area, low pressure).

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 what happens when they push a thumb tack into a board versus pushing with their finger. The teacher then relates this to the idea of force over an area.
Pupils’ Activity: Pupils respond to the questions and share their observations.
Learning Point: Pupils are introduced to the concept of force distribution and its effect.

Step 2: Defining Pressure

Time: 10 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher clearly defines pressure as force per unit area, writes the formula (P = F/A) on the board, and explains each component. The teacher uses examples like a balloon being pumped with air to illustrate.
Pupils’ Activity: Pupils listen attentively, define pressure in their own words, and write down the definition and formula.
Learning Point: Pupils understand the definition and formula of pressure.

Step 3: Pressure Units

Time: 10 minutes
Teaching Skill: Listing/Explanation
Teacher’s Activity: The teacher introduces the standard SI unit of pressure (Pascal) and explains its derivation (N/m²). The teacher then lists other common units of pressure like PSI, Bar, and atm, explaining where they are commonly used.
Pupils’ Activity: Pupils listen, ask questions for clarity, and write down the various units of pressure.
Learning Point: Pupils learn about the different units used to measure pressure.

Step 4: Examples of Pressure in Daily Life

Time: 7 minutes
Teaching Skill: Illustration/Application
Teacher’s Activity: The teacher provides practical examples of pressure from daily life and in technical applications, such as inflating tires, water pressure, and atmospheric pressure. The teacher can use the sealed bottle to demonstrate pressure changes.
Pupils’ Activity: Pupils contribute their own examples and discuss how pressure applies in these situations.
Learning Point: Pupils relate the concept of pressure to real-world scenarios.

Step 5: Practical Demonstration with Pressure Gauge

Time: 5 minutes
Teaching Skill: Demonstration
Teacher’s Activity: The teacher shows a pressure gauge and explains how it is used to measure pressure in systems. If possible, the teacher demonstrates how a pressure gauge works using an air pump and a balloon.
Pupils’ Activity: Pupils observe the demonstration and ask questions about the instrument and its function.
Learning Point: Pupils visually identify a pressure gauge and understand its practical use.

Step 6: Class Discussion and Recap

Time: 3 minutes
Teaching Skill: Discussion/Reinforcement
Teacher’s Activity: The teacher leads a brief discussion, asking pupils to summarize key points covered in the lesson and clarifying any misconceptions.
Pupils’ Activity: Pupils actively participate in the discussion, summarizing points and asking for clarification.
Learning Point: Pupils reinforce their understanding of the lesson content through verbal interaction.

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 pressure.
State the formula for calculating pressure.
Mention three common units of pressure.
Give two examples of pressure applications in daily life.

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 lesson by reiterating the definition of pressure, its formula, common units, and its importance. The teacher assigns homework: research different types of pressure (e.g., gauge pressure, absolute pressure).
Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.
Learning Point: Pupils have a consolidated understanding of the lesson and an assignment for further learning.

Lesson Keywords

Pressure – Force applied perpendicular to a surface per unit area.
Force – An influence tending to change the motion of a body or produce deformation.
Area – The extent or measurement of a surface or piece of land.
Pascal (Pa) – The SI unit of pressure, equal to one Newton per square meter.
PSI (Pounds per Square Inch) – A unit of pressure commonly used in the imperial system.
Bar – A metric unit of pressure, approximately equal to atmospheric pressure.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to calculate pressure given specific force and area values. For pupils needing more support, the teacher can provide simplified diagrams and additional one-on-one explanations, focusing on the definition and basic units.

Note for teachers using this lesson plan

Teachers should ensure that practical examples are relatable to the pupils’ environment. Encourage active participation and use visual aids to make abstract concepts of pressure more concrete. Safety precautions should be observed during any practical demonstrations involving pressure.