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.