Presentation of Concepts: Congruency

Age

6-9.

Materials

• Metal insets of the square and its subdivisions
  

Presentation

1. Invite the child to bring out the material and arrange it properly.
2. Take any two inset pieces from the same frame.
3. Note: Montessori suggests the fourths to be taken from the frame as pictured.
4. Superimpose the two pieces.
5. Indicating the surface, tell the child that every point of one figure corresponds to a point on the other figure, that is, they can be superimposed perfectly.
6. The Norwegians say that one "answers" the other, rather than on "corresponds" to the other.
7. This is a special quality that these two figures have.
8. We can say that one is congruent to the other.
9. Repeat the experience with the other fractional divisions.