To show the child that the area of all the equilateral triangles is the same.
- Have the child build the triangles as in the First Presentation.
- Say: “All these triangles are the same.”
- Pick up the gray triangle and, starting with the green triangle, place it on top of each of the others.
- Place directly on top of the others, trace the two triangles from bottom left corner, going counter clockwise, and say: This triangle is the same as this triangle” each time.
- When each of the triangles have been compared to the first one and traced, bring the gray triangle forward and place it in front of the child.
- Starting with the green triangle, build all of them on top of the gray one.
- When finished, trace around all the triangles and say:”All of these triangles are the same size.”
- Return the triangles to their proper position.
- Bring the box forward and replace the triangles in the following order:
- Gray Triangle
- Green Triangle
- Yellow Triangle
- Red Triangle
- Close the box, return the materials to the shelf
POINTS OF INTEREST
- Tracing the black lines.
- Matching the triangles.
- Superimposing the gray triangle.
- Making the one big triangle.
- Indirect superimposing when putting them back in the box.
- Naming the shapes and the various triangles used to make them.
CONTROL OF ERROR
- Black guides.
- Different colors of triangles.
DIRECT AIMS
- Showing that different sets of triangles, when put together, are equal in size to the gray triangle.
- Development of the ability to discriminate geometric forms.
- Growth in concentration and independence.
INDIRECT AIMS
- Preparation for Geometry.
- Development of appreciation of line and form.
- Development of creativity.