Grade: 8 Subject: Mathematics Topic: Finding Angles in a Triangle

Objective: - Students will be able to identify and understand the different types of angles in a triangle. - Students will be able to apply the angle sum property of a triangle to find missing angles. - Students will be able to solve problems involving angles in triangles.

Materials: - Whiteboard or blackboard - Markers or chalk - Triangle cutouts or printed triangle images - Protractors - Worksheets with triangle problems - Rulers

Procedure:

- Introduction (10 minutes):
- Begin the lesson by asking students if they know what a triangle is and how many sides and angles it has.
- Write the definition of a triangle on the board: “A triangle is a polygon with three sides and three angles.”
- Show different triangle images on the board and ask students to identify the angles in each triangle.

- Types of Angles in a Triangle (15 minutes):
- Introduce the three types of angles in a triangle: acute, obtuse, and right angles.
- Define each type of angle and provide examples on the board.
- Discuss the sum of the angles in a triangle, which is always 180 degrees.
- Write the angle sum property on the board: “The sum of the three angles in a triangle is always 180 degrees.”

- Angle Sum Property (15 minutes):
- Provide triangle cutouts or printed triangle images to each student.
- Ask students to measure the angles of their triangles using protractors.
- Instruct students to add up the three angles of their triangles and check if the sum is 180 degrees.
- Discuss the results as a class and emphasize the angle sum property.

- Finding Missing Angles (20 minutes):
- Distribute worksheets with triangle problems to each student.
- Instruct students to solve the problems by applying the angle sum property.
- Encourage students to draw diagrams and label the given angles and unknown angles.
- Circulate the classroom to provide assistance and guidance as needed.

- Group Activity (15 minutes):
- Divide the class into small groups of 3-4 students.
- Provide each group with a large triangle cutout or printed triangle image.
- Instruct the groups to measure and label the angles of their triangles.
- Ask each group to find a missing angle in their triangle and explain their solution to the class.

- Conclusion and Recap (5 minutes):
- Summarize the key points discussed in the lesson, including the types of angles in a triangle and the angle sum property.
- Ask students if they have any questions or if there are any concepts they would like to review.
- Assign homework exercises or additional practice problems related to finding angles in triangles.

Assessment: - Observe students’ participation and engagement during class activities. - Review students’ completed worksheets and group activity solutions. - Assign homework exercises to assess individual understanding. - Conduct a short quiz or exit ticket to evaluate students’ comprehension of the topic.