From 1928 to 1942, Walter Damrosch, NBC's music director, hosted the 'Music Appreciation Hour', a popular series of radio lectures on classic music. The show was broadcast during school hours, and teachers were provided with textbooks and worksheets by the network.
"Noted conductor lectures to school children via radio. Photo shows Walter Damrosch, noted orchestra leader, at the piano in the National Broadcasting studio, 711 5th Avenue, where a special program for public school children was broadcast by the symphony orchestra, during which Mr. Damrosch lectured on music. Several hundred schools received the program." -- NBC Photo, 2/14/1928