206 THE DISCOVERY OF THE CHILD
ILLUSTRATIVE APPLICATIONS: GUIDE TO THE
MATERIAL SOLID INSETS
Dimensions. The teacher, after the child has had long practice
in handling the three solid insets and has acquired confidence in
the exercise, takes all the cylinders of equal height and spreads
them out on the table close together. Then she chooses the two
extremes saying: "This is the thickest," and " This the thinnest".
She places them side by side to make the comparison more telling,
and then, taking each one of them by the knob, she places them
tase to base in order to mark the extreme difference. Then she
places them close together again and upright, in order to show
that they are of equal height. Meanwhile she may be repeating
many times: "Thick, thin". She must every time follow the
other stages of verification in which she asks: " Give me the
thickest, the thinnest," and finally the language test: " What is it
like?" In later lessons the teacher removes the two extremes and
repeats the lesson with the two remaining at the extremities.
Finally, she uses all the pieces, chooses one of them by chance,
and asks: "Give me one thicker than this, or thinner than
this."
The teacher proceeds in the same way with the second set of
solid insets. In this case she places the pieces upright, all of them
having a base wide enough to maintain them in this position.
She says: "It is the tallest, it is the shortest." Then she places
the extreme pieces in juxta-position, having removed them from
the row; she places their bases, end to end, showing that they are
equal. From the extremes she passes to the middle pieces, as in
the first exercise.
With the third set of solid insets, the teacher, after having
placed all the pieces ia a graduated row, points to the first, saying:
**It is the largest," .and to the last saying: "It is the smallest,"
Then she places them close together and points out how they differ
in height as well as in the size of the base. The proceeding is
similar to that in the two preceding exercises.