Lesson Plan: Polygon – Types and Angles in Polygons

Subject: Mathematics

Class: JSS 2

Term: Second Term

Week: 4

Topic: Polygon – Types and Angles in Polygons

Sub-topic: Definition, Types, Properties, and Angle Calculations

Behavioral Objectives

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

1. Define a polygon.
2. Identify different types of polygons.
3. State the properties of polygons.
4. Calculate the sum of interior and exterior angles of polygons.
5. Solve word problems involving angles in polygons.

Keywords

• Polygon
• Interior angles
• Exterior angles
• Regular polygon
• Irregular polygon

Set Induction (Lesson Introduction)

The teacher starts by asking students:
“Look around the classroom. Can you name objects that have multiple sides and straight edges?”
After students respond, the teacher explains that these objects are examples of polygons, which are shapes with straight sides and vertices.

Entry Behavior

Students have previous knowledge of basic shapes such as triangles, rectangles, and pentagons.

Learning Resources and Materials

• Flashcards with different polygon shapes
• Protractors and rulers for measuring angles
• Chart displaying different types of polygons and their properties

Building Background/Connection to Prior Knowledge

• The teacher reminds students about the previous lesson on angles.
• The concept of lines and angles is reviewed to help students understand how angles are formed in polygons.

Embedded Core Skills

• Critical Thinking – Identifying and classifying polygons.
• Numeracy Skills – Measuring and calculating angles.
• Problem-Solving – Applying formulas to find angles in polygons.

Learning Materials

• Lagos State Scheme of Work
• Mathematics textbooks (JSS 2)
• Online resources: Math is Fun – Polygons

Instructional Materials

• Whiteboard and markers
• Polygon cutouts
• Digital presentations (if available)

Lesson Presentation

Step 1: Introduction to Polygons

Teacher’s Activity:

• Defines a polygon as a closed shape with straight sides.
• Explains the difference between regular and irregular polygons.

Learner’s Activity:

• Students list examples of polygons they see around them.

Step 2: Types of Polygons

Teacher’s Activity:

• Lists different types of polygons:
  • Triangle (3 sides)
  • Quadrilateral (4 sides)
  • Pentagon (5 sides)
  • Hexagon (6 sides)
  • Heptagon (7 sides)
  • Octagon (8 sides)
• Discusses the properties of each polygon.

Learner’s Activity:

• Students classify polygons based on the number of sides.

Step 3: Sum of Interior Angles in Polygons

Teacher’s Activity:

• Introduces the formula:
  Sum of Interior Angles = (number of sides – 2) × 180 degrees
• Provides worked examples.

Learner’s Activity:

• Students calculate the sum of interior angles for different polygons.

Step 4: Exterior Angles of Polygons

Teacher’s Activity:

• Introduces the formula:
  Exterior Angle = 360 degrees ÷ number of sides
• Demonstrates with examples.

Learner’s Activity:

• Students solve problems involving exterior angles.

Step 5: Application and Problem Solving

Teacher’s Activity:

• Explains the use of polygons in real-life situations, such as road signs and architecture.
• Gives word problems for students to solve.

Learner’s Activity:

• Students apply the concepts to solve problems.

Evaluation Questions

1. What is a polygon?
   a) A shape with curved sides
   b) A closed shape with straight sides
   c) A three-dimensional figure
   d) A shape with no sides

2. How many sides does a hexagon have?
   a) 5
   b) 6
   c) 7
   d) 8

3. What is the sum of the interior angles of a quadrilateral?
   a) 90°
   b) 180°
   c) 360°
   d) 720°

4. What is the sum of the interior angles of a pentagon?
   a) 360°
   b) 540°
   c) 720°
   d) 900°

5. If a regular octagon has equal exterior angles, what is the measure of each exterior angle?
   a) 45°
   b) 60°
   c) 72°
   d) 90°

6. Which of the following is NOT a polygon?
   a) Triangle
   b) Circle
   c) Hexagon
   d) Decagon

7. What is the sum of the interior angles of a heptagon?
   a) 720°
   b) 900°
   c) 1080°
   d) 1260°

8. The exterior angles of any polygon sum up to:
   a) 180°
   b) 270°
   c) 360°
   d) 720°

9. A regular pentagon has an exterior angle of:
   a) 90°
   b) 72°
   c) 60°
   d) 108°

10. What is the sum of the interior angles of a decagon?
    a) 1080°
    b) 1260°
    c) 1440°
    d) 1620°

Class Activity Discussion – FAQs

1. What is a polygon?
   A polygon is a closed shape with straight sides.

2. Can a polygon have curved sides?
   No, a polygon must have straight sides.

3. How do we classify polygons?
   By the number of sides they have.

4. What is the difference between regular and irregular polygons?
   Regular polygons have equal sides and angles, while irregular polygons do not.

5. What is the sum of exterior angles of any polygon?
   360°.

6. How do you find the sum of interior angles of a polygon?
   Use the formula: (number of sides – 2) × 180°.

7. What is the exterior angle of a regular hexagon?
   60°.

8. Why do we study polygons?
   They are useful in construction, engineering, and everyday objects.

Assessment – Short Answer Questions

1. Define a polygon.
2. What is the sum of the interior angles of a nonagon?
3. Find the measure of one interior angle of a regular hexagon.
4. What is the difference between convex and concave polygons?
5. Calculate the exterior angle of a regular decagon.
6. How many sides does a dodecagon have?
7. List three real-life examples of polygons.

Conclusion

The teacher summarizes key points and assigns practice exercises.