Electronic apparatus for classroom instruction

Claim 1

IN COMBINATION, A MATRIX-SWITCHING ASSEMBLY COMPRISING FOUR CONTACT-SUPPORTING MEMBERS ASSEMBLED IN FIXED RELATION, SAID MEMBERS EACH HAVING IDENTICAL PATTERNS OF ELECTRICAL CONTACTS THEREON, THE CONTACTS RESPECTIVELY OF SAID MEMBERS BEING IN REGISTRY; A RECORDINGREPRODUCING DEVICE HAVING INPUT AND OUTPUT CIRCUITS RESPECTIVELY, SAID OUTPUT CIRCUIT BEING COUPLED TO PRESELECTED CONTACTS OF THE FIRST OF SAID MEMBERS, SAID INPUT CIRCUIT BEING COUPLED TO PRESELECTED CONTACTS OF THE FOURTH OF SAID MEMBERS; AN INSTRUCTION AMPLIFIER HAVING FIRST AND SECOND INPUT CIRCUITS AND FIRST AND SECOND OUTPUT CIRCUITS, THE FIRST INPUT CIRCUIT BEING COUPLED TO PRESELECTED CONTACTS OF THE THIRD OF SAID MEMBERS, THE FIRST OUTPUT CIRCUIT BEING COUPLED TO OTHER PRESELECTED CONTACTS OF SAID FIRST MEMBER, SAID SECOND INPUT AND OUTPUT CIRCUITS BEING COUPLED TO OTHER PRESELECTED CONTACTS OF THE SECOND AND FOURTH MEMBERS, RESPECTIVELY; SAID INSTRUCTION AMPLIFIER INCLUDING MEANS FOR PROVIDING AMPLIFIED SIGNALS IN SAID FIRST OUTPUT CIRCUIT IN RESPONSE TO SIGNALS APPLIED TO SAID FIRST AND SECOND INPUT CIRCUITS, MEANS FOR PROVIDING AMPLIFIED SIGNALS IN SAID FIRST OUTPUT CIRCUIT IN RESPONSE TO SIGNALS APPLIED TO SAID SECOND INPUT CIRCUIT, AND MEANS FOR PROVIDING AMPLIFIED SIGNALS IN SAID SECOND OUTPUT CIRCUIT IN RESPONSE TO SIGNALS APPLIED TO SAID FIRST INPUT CIRCUIT; A FIRST SOURCE OF ELECTRICAL SIGNALS COUPLED TO OTHER PRESELECTED CONTACTS OF SAID THIRD MEMBER; AT LEAST ONE STUDENT AMPLIFIER HAVING INPUT AND OUTPUT CIRCUITS, DIFFERENT OTHER PRESELECTED CONTACTS OF THE THIRD MEMBER COUPLED TO THE INPUT CIRCUIT OF SAID STUDENT AMPLIFIER, DIFFERENT OTHER PRESELECTED CONTACTS OF THE SECOND MEMBER COUPLED TO THE OUTPUT CIRCUIT OF SAID