This hands-on activity instructs students to draw and cut out a triangle from paper, label and remove each interior angle, and rearrange the angles so that their vertices meet at one point with no overlap. Doing so demonstrates that the sum of the interior angles of a triangle equals 180 degrees.

1. DISCOVERING WITH
HANDS-ON METHOD

2. 1. On a piece of plain white paper, draw a
triangle and cut it out.

3. 2. Label the interior of each angle and tear off
each.

4. 3. Now tear off each corner of the triangle and
rearrange the 3 “angles” so that their vertices
meet at one point with no overlap.

5. 3. Now tear off each corner of the triangle and
rearrange the 3 “angles” so that their vertices
meet at one point with no overlap.

6. 4. What does this tell you about sum of the
angles in the triangle?