| 摘要 |
A teaching apparatus comprising a printed sheet carrying questions and for each question a number of demarked areas denoting different answers, a platen locatable behind the sheet and bearing a plurality of separate electrically conductive areas registrable with the sheet demarked areas, a probe in circuit with the conductive areas and connectable to an electric energy source, and a multivibrator for applying to the conductive areas at will periodically time-varying signals separable to a receiver T1 and capable of causing from the conductive areas radiation of corresponding electromagnetic waves capable of being sensed in front of the sheet by the probe touching the sheet, the receiver T1 being coupled to the probe to identify the wave picked up thereby and actuating indicating means indicating the correctness of the selected answer. |
