Mathematics - Junior Secondary 2 - Angles and polygon

Angles and polygon

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TERM: 3RD TERM

WEEK 1

Class: Junior Secondary School 2
Age: 13 years
Duration: 40 minutes of 5 periods
Subject: Mathematics
Topic: Angles and Polygon
Focus: Definition and Construction of Angles, Definition of Polygons

SPECIFIC OBJECTIVES:

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

  1. Define angles and identify different types of angles (acute, obtuse, right, etc.).
  2. Construct and measure specific angles (75°, 105°, 120°, 135°) using a protractor.
  3. Define polygons and recognize different types with examples (triangle, quadrilateral, pentagon, etc.).
  4. Apply knowledge of angles to construct and identify polygons in diagrams.

INSTRUCTIONAL TECHNIQUES:

  • Question and answer
  • Guided demonstration
  • Discussion
  • Hands-on activities (using protractors)
  • Visual aids (diagrams and drawings)

INSTRUCTIONAL MATERIALS:

  • Protractors
  • Rulers
  • Whiteboard and marker
  • Flashcards of polygons
  • Worksheets

 

PERIOD 1 & 2: Define and Construct Angles

PRESENTATION:

Step

Teacher’s Activity

Pupil’s Activity

Step 1 - Introduction

Explains the concept of angles (acute, obtuse, right).

Pupils listen and ask questions.

Step 2 - Explanation

Defines the construction of different angles, such as 75°, 105°, 120°, 135°. Demonstrates using protractors.

Pupils observe and practice constructing these angles.

Step 3 - Demonstration

Draws the angles on the board, explaining how to measure with a protractor.

Pupils follow along and practice measuring angles with protractors.

Step 4 - Practice

Pupils construct their own angles (75°, 105°, 120°, 135°) on paper using protractors.

Pupils draw and label angles.

NOTE ON BOARD:

  • Acute Angle: An angle less than 90°
  • Right Angle: An angle of exactly 90°
  • Obtuse Angle: An angle greater than 90° but less than 180°
  • Straight Angle: An angle of 180°

EVALUATION (5 exercises):

  1. Construct a 75° angle.
  2. Measure and write the size of the angle between two intersecting lines in the classroom.
  3. Draw an acute angle and an obtuse angle.
  4. Construct a 120° angle.
  5. Draw a straight angle.

CLASSWORK (5 questions):

  1. Construct a 90° angle using a protractor.
  2. Measure the angle formed by the clock’s hands at 3:00 PM.
  3. What is the difference in size between a 90° and 120° angle?
  4. Draw a 135° angle.
  5. Write the degree measure of an obtuse angle.

ASSIGNMENT (5 tasks):

  1. Construct a 105° angle.
  2. Measure and record the angle formed by a book cover.
  3. Draw an acute and an obtuse angle on a worksheet.
  4. Write the properties of a right angle.
  5. Draw and label three different types of angles in real life.

 

PERIOD 3 & 4: Define and Identify Polygons

PRESENTATION:

Step

Teacher’s Activity

Pupil’s Activity

Step 1 - Introduction

Defines polygons and explains their properties.

Pupils listen and participate in a discussion.

Step 2 - Explanation

Gives examples of polygons (triangle, quadrilateral, pentagon, hexagon, etc.). Shows how to identify the number of sides and angles.

Pupils ask questions and observe examples.

Step 3 - Demonstration

Draws various polygons on the board (triangle, square, pentagon) and labels the sides and angles.

Pupils observe and practice drawing polygons.

Step 4 - Practice

Pupils draw polygons of different types and identify their sides and angles.

Pupils draw and label polygons on their worksheets.

NOTE ON BOARD:

  • Polygon: A closed figure with straight sides.
  • Triangle: A polygon with three sides.
  • Quadrilateral: A polygon with four sides.
  • Pentagon: A polygon with five sides.
  • Hexagon: A polygon with six sides.

EVALUATION (5 exercises):

  1. Draw a triangle and label its sides.
  2. Identify the number of sides and angles in a quadrilateral.
  3. Draw a pentagon and count the number of sides.
  4. Draw a hexagon and list its properties.
  5. Identify whether a given figure is a polygon.

CLASSWORK (5 questions):

  1. Draw and label a triangle.
  2. Identify the type of polygon with seven sides.
  3. Draw a quadrilateral and measure its angles.
  4. How many sides does a hexagon have?
  5. Name a polygon with 5 sides and draw it.

ASSIGNMENT (5 tasks):

  1. Draw a polygon with 4 sides and 90° angles.
  2. Write the properties of a hexagon.
  3. Draw a decagon (10 sides) and label it.
  4. Identify polygons from pictures in the environment.
  5. Create a word problem involving polygons.

 

PERIOD 5: Review of Angles and Polygons

PRESENTATION:

Step

Teacher’s Activity

Pupil’s Activity

Step 1 - Introduction

Recap of key concepts: types of angles and polygons.

Pupils participate in the recap.

Step 2 - Explanation

Ask students to solve practical examples involving angles and polygons.

Pupils solve the problems individually.

Step 3 - Drill

Walk around the classroom while pupils solve a few more angle and polygon-related problems.

Pupils solve problems on their own and ask questions when needed.

Step 4 - Discussion

Discuss answers and clarify any misc#onceptions.

Pupils ask questions and clarify doubts.

EVALUATION (5 questions):

  1. What is the sum of the interior angles of a triangle?
  2. How many sides does a pentagon have?
  3. Draw an acute and obtuse angle.
  4. Identify the polygon with four sides and 90° angles.
  5. How do you calculate the sum of the interior angles of a polygon?

CLASSWORK (5 tasks):

  1. Identify whether a shape is a polygon or not.
  2. Calculate the sum of the interior angles of a quadrilateral.
  3. Measure the angles of a given triangle.
  4. Construct a polygon with 5 sides.
  5. Draw a regular polygon and state its properties.

ASSIGNMENT (5 tasks):

  1. Write down the sum of the interior angles of a hexagon.
  2. Solve the following: Find the number of sides of a polygon whose interior angles sum to 1,080°.
  3. Draw a regular octagon.
  4. Write the names of polygons based on their number of sides.

Create a diagram showing an acute angle and an obtuse angle.