Class: Junior Secondary School 1 (JSS 1 / JS1)
Term: 3rd Term
Week: 5
Age: 12 years
Duration: 45 minutes
Subject: Mathematics
Curriculum Theme: Geometry
Previous Lesson: Construction, Constructing Parallel and Perpendicular Line.
Topic: Angles
Subject Matter: Meaning and measurement: Definition and identification of adjacent, alternate, corresponding and vertically opposite angles.

Specific Objectives

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

Cognitive Domain:

Define an angle.
Identify adjacent, alternate, corresponding, and vertically opposite angles from diagrams.
State the properties of vertically opposite, alternate, and corresponding angles when lines are parallel.

Affective Domain:

Appreciate the presence of angles in their environment.
Pay close attention to the teacher’s explanations and demonstrations.

Psychomotor Domain:

Draw and label different types of angles.
Measure angles using a protractor.

Work collaboratively with peers to identify different angles in given figures.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Junior Secondary Schools.
State Unified Scheme of Work.
New General Mathematics for Junior Secondary Schools 1.
https://www.mathsisfun.com/geometry/angles-alternate-corresponding.html
https://www.khanacademy.org/math/geometry/hs-geo-parallels-transversals/hs-geo-angles-and-lines/v/angles-formed-by-a-transversal

Instructional Materials

The teacher will teach this lesson with the aid of:

A protractor and ruler.
Chalkboard and chalk.
Charts showing different types of angles (adjacent, alternate, corresponding, vertically opposite) formed by intersecting lines and parallel lines cut by a transversal.

Rationale for the Lesson

Understanding angles is important for pupils because angles are fundamental in geometry and are found in many real-world applications, such as in architecture, engineering, and everyday objects. This lesson helps pupils to correctly identify and classify different types of angles based on their positions and relationships.

Prerequisite/Previous Knowledge

Pupils have prior knowledge of basic geometric shapes, lines, and how to use a ruler.

Lesson Content/Board Summary

Angles

Definition of an Angle

An angle is formed when two straight lines or rays meet at a common endpoint. The common endpoint is called the vertex, and the two lines are called the arms or sides of the angle.

Types of Angles Based on Position/Relationship

When two or more lines intersect or are cut by a transversal, specific relationships between the angles formed are observed.

Adjacent Angles

Adjacent angles are two angles that share a common vertex and a common side, but do not overlap. They lie next to each other.

Example: In a diagram where angles AOB and BOC share vertex O and side OB, they are adjacent angles. (Teacher will draw an illustration.)

Vertically Opposite Angles

Vertically opposite angles are formed when two straight lines intersect. They are the angles directly opposite each other at the point of intersection.

Property: Vertically opposite angles are always equal.
Example: If lines AB and CD intersect at O, then angle AOC and angle BOD are vertically opposite and are equal. Similarly, angle AOD and angle BOC are vertically opposite and are equal. (Teacher will draw an illustration.)

Alternate Angles

Alternate angles are formed when a transversal line intersects two parallel lines. They are on opposite sides of the transversal and between the parallel lines (interior alternate angles) or outside the parallel lines (exterior alternate angles).

Property: When the lines are parallel, alternate interior angles are equal.
Example: If line EF cuts parallel lines AB and CD, and angle AGH is formed on one side and angle GHD on the opposite side between the parallel lines, then angle AGH = angle GHD. (Teacher will draw an illustration.)

Corresponding Angles

Corresponding angles are formed when a transversal line intersects two other lines (usually parallel). They are in the same relative position at each intersection.

Property: When the lines are parallel, corresponding angles are equal.
Example: If line EF cuts parallel lines AB and CD, and angle EGB is formed above AB on the left, and angle GHD is formed above CD on the left, then angle EGB = angle GHD. (Teacher will draw an illustration.)

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 identify objects in the classroom that have corners or openings, such as doors, windows, and desks. The teacher then explains that these corners represent angles.
Pupils’ Activity: Pupils respond to the greetings and identify objects with corners in the classroom.
Learning Point: Pupils are introduced to the concept of angles through familiar objects.

Step 2: Definition of an Angle

Time: 5 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines an angle, its vertex, and its arms. The teacher draws an angle on the board and labels its parts.
Pupils’ Activity: Pupils listen attentively and copy the definition and diagram into their notebooks.
Learning Point: Pupils learn the formal definition and basic components of an angle.

Step 3: Adjacent Angles

Time: 5 minutes
Teaching Skill: Demonstration/Illustration
Teacher’s Activity: The teacher explains what adjacent angles are, emphasizing the shared vertex and common side. The teacher draws an example of adjacent angles on the board and points out their features.
Pupils’ Activity: Pupils observe the diagram and explanation, then copy the definition and example into their notes.
Learning Point: Pupils understand and can identify adjacent angles.

Step 4: Vertically Opposite Angles

Time: 5 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher draws two intersecting straight lines on the board and explains how vertically opposite angles are formed. The teacher states and demonstrates the property that vertically opposite angles are equal.
Pupils’ Activity: Pupils watch the demonstration, listen to the explanation, and copy the definition, property, and diagram.
Learning Point: Pupils learn to identify and state the property of vertically opposite angles.

Step 5: Alternate Angles

Time: 7 minutes
Teaching Skill: Illustration/Explanation
Teacher’s Activity: The teacher draws two parallel lines intersected by a transversal line. The teacher then explains and identifies alternate interior angles, emphasizing their position and property when the lines are parallel.
Pupils’ Activity: Pupils observe the diagram and explanation carefully, then draw the diagram and write down the definition and property.
Learning Point: Pupils understand the concept of alternate angles and their property in parallel lines.

Step 6: Corresponding Angles

Time: 7 minutes
Teaching Skill: Illustration/Explanation
Teacher’s Activity: The teacher uses the same diagram of parallel lines and a transversal. The teacher explains and identifies corresponding angles, highlighting their similar positions at each intersection and their property when the lines are parallel.
Pupils’ Activity: Pupils pay attention to the explanation, draw the diagram, and note the definition and property of corresponding angles.
Learning Point: Pupils learn to identify and state the property of corresponding angles.

Step 7: Evaluation/Review

Time: 5 minutes
Teaching Skill: Questioning/Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

What is an angle?
Define adjacent angles.
When two straight lines intersect, what can you say about the angles opposite each other?
Draw two parallel lines intersected by a transversal and label a pair of alternate angles.
Draw two parallel lines intersected by a transversal and label a pair of corresponding angles.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 1 minute
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definitions and properties of the different types of angles discussed. The teacher then assigns homework from the textbook.
Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.
Learning Point: Pupils consolidate their learning and are given further practice.

Home Task: Solve three new exercises on Angles. Show each step and check each answer.

Lesson Keywords

Angle – Formed by two rays sharing a common endpoint.
Adjacent – Angles sharing a common vertex and side.
Alternate – Angles on opposite sides of a transversal between parallel lines.
Corresponding – Angles in the same relative position at each intersection of a transversal with parallel lines.
Vertically opposite – Angles opposite each other when two lines intersect.

Differentiation

For pupils who grasp the concepts quickly, the teacher will provide additional problems involving finding unknown angles using the properties discussed. For pupils needing more support, the teacher will work through more examples on the board, offering one-on-one guidance and simplifying explanations.

Note for teachers using this lesson plan

Teachers should ensure to use clear and large diagrams when illustrating the different types of angles. Encourage pupils to actively participate by identifying angles in various diagrams. Practical examples from the classroom environment can help reinforce understanding. Emphasize the conditions under which alternate and corresponding angles are equal (i.e., when the lines are parallel).