Working model to Triangle Angle Sum Theorem

Creating a working model to illustrate the Triangle Angle Sum Theorem using cardboard and syringes can be a creative and interactive project.

The Triangle Angle Sum Theorem states that the sum of the three interior angles of a triangle is always equal to 180 degrees.


  1. Cardboard
  2. Ruler
  3. Pencil
  4. Craft knife or scissors
  5. Protractor
  6. Syringes (3)
  7. Straws or flexible tubing
  8. Split pins (brads)
  9. String or yarn
  10. Glue or tape
  11. Markers or colored pencils

Step by Step working model of Triangle Angle Sum Theorem

  1. Create Triangles from Cardboard:
    • Cut out three different triangles from the cardboard, ensuring that each triangle has a clear and distinct shape. The triangles can be of various sizes and shapes.
  2. Label the Triangles:
    • Label the vertices of each triangle as A, B, and C. You can write these labels directly on the cardboard.
  3. Measure and Cut Angles:
    • Use a protractor to measure and cut out angles from the triangles. Ensure that the angles of each triangle add up to 180 degrees, illustrating the Triangle Angle Sum Theorem.
  4. Attach Syringes to Represent Angles:
    • Cut small pieces of straws or flexible tubing and attach them to the vertices of each triangle using glue or tape. These will act as connectors for the syringes.
  5. Connect Syringes with Tubing:
    • Attach the syringes to the tubing or straws so that the plunger of each syringe can move freely. Use split pins (brads) to secure the syringes in place.
  6. Label Syringes:
    • Label each syringe with the measure of the corresponding angle. For example, if one angle is 60 degrees, label the syringe with “60.”
  7. Create a Base:
    • Cut out a larger piece of cardboard to act as the base for your model. Attach the triangles to this base.
  8. Attach Strings for Visualization:
    • Attach strings or yarn to the vertices of the triangles, connecting them to the syringes. This will allow you to pull on the strings and change the angles, demonstrating the Triangle Angle Sum Theorem.
  9. Decorate and Color:
    • Use markers or colored pencils to decorate the triangles and syringes. This can make the model more visually appealing.
  10. Demonstration
    • Demonstrate the model by pulling on the strings and observing how the syringes move. Explain that, no matter how the angles change, the sum of the interior angles of a triangle always equals 180 degrees.

Leave a Comment