Innovative
Classroom

Center Focus

Discovering the Area of Triangles

  1. You will need Geoboards and rubberbands for this activity.
  2. Have students make any triangle they wish on the Geoboard, keeping one side parallel to the side of the Geoboard. This side will be called the Base.
  3. Students will then find the area of that triangle. The area is found assuming the following: The smallest square on the board equals one unit of area, and the side of that square is one unit of length.
  4. Have students do this for at least four other triangles, recording their data as they go.
  5. Ask students if they can find a pattern and devise a formula that will always work for any triangle. The point of this exercise is to see if the students can come up with the formula for the area of triangles, which is
    A=(1/2)x(base)x(height).
  6. If you want to give them a hint in finding the formula, tell students to make two of the same triangles and form them into a parallelogram.
  7. You may want to have your kids use this Geoboard pattern to show how they found the area.

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