Interior Angles of a Triangle Experiment

A triangle is a polygon with 3 sides and 3 angles?

The types of triangles are equilateral, isosceles, scalene, and right. 

In this experiment, students will predict the sum of all 3 interior angles of a particular triangle. Then they will predict if the different kinds of  triangles have the same sum for their interior angles.

Materials

• paper
• pencil
• marker (optional)
• ruler
• protractor
• scissors

Directions

• Have students draw 3 different types of triangles and cut out each one.

• Mark each angle. Use a square for right angles and a curved line for all other angles.

• Have the student choose one of the triangles.
• Predict the sum of all 3 interior angles.
• Cut off the corners of the triangle

• Place the cut pieces on a protractor next to each other. (The points of the angles should touch the center of the protractor.)

• What is the sum of all 3 angles?
• Next predict if the answer will be the same for the other triangles.
• Repeat the steps above for the other triangles
• Was the prediction correct? What is the sum of the interior angles in a triangle?

The sum of all the angles in a triangle = 180 degrees.

Have fun with angles!

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