Lesson Note: Angles

Subject: Mathematics

Class: JSS 2

Term: Second Term

Week: 3

Topic: Angles

1. Behavioral Objectives

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

1. Define and identify different types of angles.
2. Measure and classify angles correctly.
3. State and apply angle properties in problem-solving.
4. Solve real-life problems involving angles.
5. Differentiate between complementary, supplementary, and vertically opposite angles.

2. Keywords

• Angle
• Acute
• Right
• Obtuse
• Reflex
• Complementary
• Supplementary
• Vertically Opposite

3. Set Induction (Introduction)

The teacher asks students to look around the classroom and identify objects that form angles, such as doors, tables, and corners of books. The teacher then explains that angles are formed when two lines meet at a point.

4. Entry Behavior

Students are already familiar with basic geometric shapes and lines from previous lessons.

5. Learning Resources and Materials

• Protractor
• Ruler
• Whiteboard and marker
• Chart showing different types of angles
• Geometric set

6. Building Background/Connection to Prior Knowledge

The teacher reminds students about the properties of lines and shapes and how they relate to angles.

7. Embedded Core Skills

• Critical thinking
• Problem-solving
• Observation
• Measurement

8. Learning Materials

• Lagos State Scheme of Work
• Mathematics textbook
• Worksheets with angle problems

9. Reference Books

• Lagos State Scheme of Work
• New General Mathematics for JSS 2
• Essential Mathematics for Junior Secondary Schools

10. Instructional Materials

• Charts displaying different angles
• Videos or animations on angles
• Protractors and rulers for measuring angles

11. Lesson Content

Definition of Angles

An angle is formed when two lines meet at a point. The point where they meet is called the vertex.

Types of Angles

1. Acute Angle: An angle that is less than 90°.
2. Right Angle: An angle that is exactly 90°.
3. Obtuse Angle: An angle that is more than 90° but less than 180°.
4. Straight Angle: An angle that is exactly 180°.
5. Reflex Angle: An angle that is more than 180° but less than 360°.
6. Complete Angle: An angle that is exactly 360°.

Angle Properties and Theorems

1. Vertically Opposite Angles: Angles opposite each other when two lines intersect are equal.
2. Complementary Angles: Two angles that add up to 90°.
3. Supplementary Angles: Two angles that add up to 180°.
4. Angles on a Straight Line: Angles on a straight line sum up to 180°.
5. Angles in a Triangle: The sum of the angles in a triangle is always 180°.

Measuring and Drawing Angles

• Use a protractor to measure an angle by placing the center of the protractor on the vertex and reading the correct scale.
• Draw an angle by marking a baseline, placing the protractor, and marking the required degree.

12. Evaluation Questions (Multiple Choice – 15 Questions)

1. An angle that measures exactly 90° is called a:
   a) Acute Angle
   b) Right Angle
   c) Obtuse Angle
   d) Reflex Angle

2. The sum of two complementary angles is:
   a) 90°
   b) 180°
   c) 360°
   d) 45°

3. A straight angle measures:
   a) 180°
   b) 90°
   c) 45°
   d) 360°

4. If one angle in a complementary pair is 65°, the other angle is:
   a) 15°
   b) 25°
   c) 35°
   d) 55°

5. An angle greater than 90° but less than 180° is:
   a) Right Angle
   b) Reflex Angle
   c) Obtuse Angle
   d) Straight Angle

6. A full revolution is equal to:
   a) 90°
   b) 180°
   c) 270°
   d) 360°

7. Vertically opposite angles are always:
   a) Equal
   b) Different
   c) Less than 90°
   d) Greater than 180°

8. A triangle has angles 50° and 60°. The third angle is:
   a) 70°
   b) 90°
   c) 80°
   d) 60°

9. If two angles are supplementary and one is 110°, the other is:
   a) 60°
   b) 70°
   c) 80°
   d) 90°

10. The sum of the angles in a quadrilateral is:
    a) 180°
    b) 270°
    c) 360°
    d) 450°

11. The measure of an obtuse angle is always:
    a) Less than 90°
    b) More than 90° but less than 180°
    c) More than 180°
    d) Equal to 90°

12. The sum of angles on a straight line is:
    a) 90°
    b) 180°
    c) 270°
    d) 360°

13. What is the missing angle in a triangle with angles 30° and 50°?
    a) 90°
    b) 100°
    c) 110°
    d) 180°

14. The angle at a point is always:
    a) 180°
    b) 270°
    c) 360°
    d) 90°

15. If an angle is 150°, its reflex angle is:
    a) 30°
    b) 120°
    c) 210°
    d) 240°

13. Class Activity Discussion – FAQs (15 Questions with Answers)

1. What is an angle?

   • An angle is formed when two lines meet at a common point.

2. What is a protractor used for?

   • A protractor is used to measure angles.

3. What are the main types of angles?

   • Acute, Right, Obtuse, Straight, Reflex, and Complete angles.

4. How many degrees are in a complete revolution?

   • 360°.

5. What are vertically opposite angles?

   • They are equal angles formed when two lines intersect.

6. What are complementary angles?

   • Two angles that add up to 90°.

7. What are supplementary angles?

   • Two angles that add up to 180°.

8. What is an obtuse angle?

   • An angle greater than 90° but less than 180°.

9. What is the angle sum in a triangle?

   • 180°.

10. What are angles on a straight line?

• Angles that sum up to 180°.

14. Assessment – Short Answer Questions (10 Questions)

1. Define an angle.
2. Name four types of angles.
3. What is the sum of angles on a straight line?
4. What is the measure of a right angle?
5. What is an acute angle?
6. How many degrees make a full circle?
7. What is the sum of angles in a quadrilateral?
8. Find the missing angle in a triangle with angles 40° and 90°.
9. What is a reflex angle?
10. If an angle measures 120°, what is its supplementary angle?

15. Conclusion and Recap

• The teacher summarizes the lesson.
• Students ask and answer final questions.
• Homework is given on measuring angles using a protractor.