Rhombus.
{ Rhomboid.
{ Trapezoid.
In combination. { Trapezium.
{ Pentagon.
{ Hexagon.
{ Heptagon.
{ Octagon.

6. The law of Mediation of Contrasts is shown in the forms of the
gift. We have in the triangles, for instance, two lines running in
opposite directions, connected by a third, which serves as the
mediation. Contrasts and their mediations are also shown in the
squares and in the forms made by combination. This gift, representing
the plane, is a link between the divided solid and the line.

* * * * *

Step from Solid to Plane.

We have now left the solid and are approaching abstraction when we
begin the study of planes. All mental development has ever begun and
must begin with the concrete, and progress by successive stages toward
the abstract, and it was Froebel's idea that his play-material might
be used to form a series of steps up which the child might climb in
his journey toward the abstract.

Beginning with the ball, a perfect type of wholeness and unity, we are
led through diversity, as shown in the three solids of the second
gift, toward divisibility in the Building Gifts, and approximation to
surface in the sixth gift. The next move in advance is the partial
abstraction of surface, shown in the tablets of the seventh gift.

The tablets show two dimensions, length and breadth, the thickness
being so trifling relatively that it need not be considered, as it
does not mar the child's perception and idea of the plane. They are
intended to represent surfaces, and should be made as thin as is
consistent with durability.

Systematic Relation between the Tablets.

The various tablets as first introduced in Germany and in this country
were commonly quite different in size and degrees of angles in the
different kindergartens, as they were either cut out hastily by the
teachers themselves, or made by manufacturers who knew very little of
the subject. The former practice of dividing an oblong from corner to
corner to produce the right-angled scalene triangle was much to be
condemned, as it entirely set aside the law of systematic relation
between the tablets and rendered it impossible to produce the standard
angles, which are so valuable a feature of the gift.

"One of the principal adv