Instruction apparatus for classrooms

Claim 1

A MATRIX-SWITCHING ASSEMBLY COMPRISING FOUR SHEETLIKE BOARDS OF INSULATING MATERIAL, SAID BOARDS BEING SECURED TOGETHER IN PARALLEL SPACED-APART RELATIONSHIP, ALL OF SAID BOARDS HAVING APERTURES THEREIN, SAID APERTURES IN IN A GIVEN BOARD BEING SPACED APART AND ARRANGED IN A PREDETERMINED PATTERN, THE APERTURE PATTERNS FOR THE REMAINING BOARDS BEING IDENTICAL AND ALIGNED IN REGISTRY WITH EACH OTHER, SAID APERTURES BEING PROVIDED WITH CONTACTS, THE CONTACTS OF THE RESPECTIVE BOARDS BEING FURTHER ARRANGED INTO A PLURALITY OF SEPARATE GROUPS, THE CONTACTS OF EACH GROUP BEING CONDUCTIVELY CONNECTED TOGETHER, AND A PLURALITY OF SELECTOR PINS INDIVIDUALLY IN SERTABLE THROUGH A RESPECTIVE SET OF REGISTERED APERTURES IN THE FOUR BOARDS, SAID PINS BEING SELECTIVELY MOVABLE IN SAID APERTURES TO FIRST AND SECOND POSITIONS, SAID PINS EACH HAVING A CIRCUIT CONNECTOR THEREON WHICH IS ENGAGEABLE WITH THE CONTACTS OF THE RESPECTIVE APERTURES RECEIVING THE PIN, MEANS INCLUDING SAID CIRCUIT CONNECTOR FOR INTERCONNECTING THE CONTACTS OF ONLY TWO ALTERNATE BOARDS WHEN THE PIN IS MOVED TO SAID FIRST POSITION AND FOR INTERCONNECTING THE CONTACTS OF THE SAME TWO AS WELL AS THE CONTACTS OF THE REMAINING TWO ALTERNATE BOARDS WHEN THE PIN IS MOVED TO SAID SECOND POSITION, WHEREBY THE CONTACTS OF THE DIFFERENT BOARDS MAY BE CONNECTED IN CIRCUIT WITH EACH OTHER.