An electronic learning/teaching device operates with and without a printed sheet element having an arrangement of selectable content by means of a user responsive sensor array beneath a surface configured to receive the element. The sensor array is formed by cross-points of two sets of crossing conductive lines, one set being driven sequentially with a radio frequency square wave and the other set being sampled sequentially though a high impedance amplifier connection with an asynchronous detection circuit. Where more than one cross-point location is user activated, algorithms are used to identify one cross-point sensor location as the user activated selection.

 
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> Method and apparatus for position tracking and communication within a defined locale

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