Abstract: Apparatus for enhancing the educational quality of verbal classroom instruction by conditioning students and teachers to pause for a pre-selected time interval before beginning to speak following the statement of a question or an answer. The apparatus includes a pair of lamps perceptible to both teacher and students operable in response to voice-actuated timing and switching circuitry. A perceptible indication, such as the extinguishment of one lamp and lighting of the other, is provided at the expiration of a selected time interval following completion of a statement, as indicated by the absence of audio signals during the interval. Circuitry is provided for selectively varying both sound level sensitivity and duration of the time interval.