Mathematic teaching aid

Claim 1

A MATHEMATICAL TEACHING AID COMPRISING A FLAT BOARD PROVIDED WITH A PLURALITY OF HOLES IN ONE FACE THEREOF, SAID HOLES BEING ARRANGED IN THE PATTERN OF A RECTANGULAR GRID REPRESENTING POINTS IN TWO DIMENSIONAL SPACE, SAID BOARD FURTHER INCLUDING, IN SAID ONE FACE, A SINGLE HORIZONTAL CENTRALLY ORIENTATED GROOVE AND A SINGLE VERTICAL CENTRALLY ORIENTATED GROOVE REPRESENTING RECTANGULAR COORDINATE AXES, HORIZONTAL AND VERTICAL LINES EXTENDING THROUGH THE CENTERS OF ALL OF THE HOLES SO AS TO PROVIDE A RECTANGULAR GRAPH ON SAID ONE FACE, AND INDICATORS FREELY RECEIVABLE WITHIN SAID HOLES AND SAID GROOVES IN A MANNER SO AS TO PROJECT OUTWARDLY THEREFROM, AND A PLURALITY OF RIGID PLANAR MATHEMATICAL FORMS, SAID FORMS EACH BEING SMALLER THAN THE BOARD AND SELECTIVELY POSITIONABLE ON SAID ONE FACE THEREOF IN OVERLYING RELATION TO THE HOLES, GROOVES AND LINES THEREON, SAID FORMS INCLUDING HOLES, GROOVES AND LINES OF THE SAME SIZE AND SPACING AS THE BOARD HOLES, GROOVES AND LINES WITHIN THE LIMIT OF EACH FORM, SAID FORMS BEING RELEASABLY SECURABLE TO SAID BOARD BY SAID INDICATORS WITH THE FORM HOLES, GROOVES AND LINES ALIGNED WITH THE BOARD HOLES, GROOVES AND LINES; SAID GROOVES BEING OF GREATER WIDTH THAN SAID HOLES AND COEXTENSIVE WITH A CENTRALLY ORIENTATED HORIZONTAL ROW OF HOLES AND A CENTRALLY ORIENTATED VERTICAL ROW OF HOLES, THE INDICATORS RECEIVABLE IN SAID GROOVES HAVING THE LOWER PORTIONS THEREOF OF A GREATER CROSS-SECTIONAL AREA THAN THE UPPER PORTIONS, THE CROSS-SECTIONAL AREA OF THE UPPER PORTIONS OF THE GROOVES INDICATORS BEING THE SAME AS THE CROSS-SECTIONAL AREA OF THE HOLE INDICATORS, SAID UPPER PORTIONS BEING RECEIVABLE IN SAID HOLES.