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Session 37: Triangles

Session Title

Triangle

Objective

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


  1.  Identify and name triangles based on sides and angles.
  2.  Understand that a triangle has 3 sides and 3 angles.
  3.  Discover and state that the sum of the interior angles of a triangle is 180°.
  4.  Collaborate in groups and reflect on their learning.

Concept

The world of triangles

Materials Required
  1. Pictures of triangle, square, rectangle, circle
  2. Instruments box
  3. Board & Chalk
  4. A4 sheet & Crayons 
  5. Work sheet

Methodology

Activity oriented

Session Duration

 90 Minutes

Introduction  Activity (15 minutes) 

Mandala Patterns (25 minutes)

Concepts:

    Concepts: Circles, radial symmetry, angles, pattern repetition

    How:

    How:

    Students use compasses and protractors to make mandalas.

    Emphasizes symmetry and repeated geometric patterns.

    Can be colored for relaxing mindfulness activity too.

    Example:-

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    Main Activity (70 minutes)

    What’s a Triangle?   Discussion (10 minutes)

    Show pictures of different shapes (triangle, square, rectangle, circle).

    Ask: Which one is a triangle? How do you know?

    Students share prior knowledge.

    Teacher highlights:

    A triangle has 3 sides and 3 angles. It’s a closed shape.

    STORYStory TIME:-Time :  (15 minutes )

    In the Triangle Kingdom, every triangle has a secret code: its 3 angles must always work together to form a straight line (180°) to keep the kingdom safe!

    Characters:-

       Prince Equi (Equilateral)

       Sir Righty (Right triangle)

       Lady Acuta (Acute triangle)

       General Obtusa (Obtuse triangle)

      The sum of the interior angles of any triangle is always equal to 180 degrees.

      In mathematical notation, for a triangle ABC with interior angles angle A, angle B, and angle C, the triangle sum theorem can be expressed as:

      ‹A + ‹ B + ‹C = 180⁰

      Ask:Ask: Can you guess how their angles work together?  

      Student Engagement:-    (10 minutes )

      Ask students to act out triangle characters (e.g., stretch arms to represent different angles).

      Key Concept : ( 10 minutes )

      Definition of a triangle:triangle

      • A closed figure with 3 sides and 3 angles.

      Types of triangles by sides:sides

      • Equilateral (3 equal sides)
      • Isosceles (2 equal sides)
      • Scalene (no equal sides)

      Types of triangles by angles:angles

      • Acute triangle (all angles < 90°)
      • Right triangle (one angle = 90°)
      • Obtuse triangle (one angle > 90°)

      Group Activity:-Activity- Angle Detectives (20 minutes )

      Make students into small groups(3 or 4)

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        Give each group a work sheet of  triangle with one missing angle.

        Students solve for the missing angle by subtracting from 180°.

        Review Questions(5 minutes)

          What is a triangle? How many angles does a triangle have?

          Follow up Task (5 minutes)

            Name a real-life object or structure that uses a triangle shape. Why is it used?

            Draw a triangle where one angle is 90°. What type of triangle is it?


            Expected Learning  Outcome:

            Knowledge building-

            • This focuses on conceptual understanding and facts. You help students understand what a triangle is, its types, and properties.

            Skill Building-building-

            • Conceptual understanding

            • Problem solving


            Review Questions/Assessment/Tasks 


            Follow up Tasks

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