In 1937, Cage got a position at the elementary school of the University of California, Los Angeles (UCLA). He worked as accompanist, percussion teacher and collaborated with dancers as performer and composer. These activities brought him towards the development of the rhythmic structures aforementioned, essentials in working with dancers, or the invention of a new instrument: the water gong. The water gong origin is due to a commission of an aquatic ballet by the UCLA swimming team. The swimmers could not hear the music when they were submerged, but Cage discovered that if he sunk a gong after beating it, they could heart it and were consequently able to adjust better to the music. The main characteristic of this instrument is that the gong´s frecuency lowers when it is partially submerged in a liquid, that is to say, it does a descending glissando when we submerge it and ascending glissando when we raise it.
That year, Xenia Cage, his wife, began as bookmaker apprentice with Hazel Dreis. Dreis forced all her apprentices to move to her mansion in Santa Monica. Cage took advantage of this situation by asking the other apprentices, together with his wife and himself, for a part of their free time to form a percussion ensemble . They played music that Cage composed using kitchen utensils, binding material, junk, etc. Although members of this ensemble were not professional musicians, they rehearsed everyday acquiring a high level of performance. This fact, along with his marriages economic hardship, prevented him from buying instruments, and are the conceptual basis of works such as Living Room Music (1940) or First Contruction (in Metal) (1939).
In the summer of 1938, Cage and his wife moved to Seattle, where one year earlier, Cage had given his famous lecture "The Future of Music: Credo". This conference, organized by B. Bird in an artistic society, was vital for the upcoming development of contemporary music. In this second time, Cage found a stable position at the Cornish School through composer Lou Harrison, with whom he shared ideas about composing for percussion and dance. During his stay at the Cornish School, Cage accompanied the dancer Bonnie Bird, composed new music for specific performances and continued developing his percussion ensemble. In that situation, First Construction (in Metal) was premiered on December 9th 1939.
At the beginning of the 1940s, Cage was constantly looking for new sounds: exotic instruments (cowbells, oxen bells, teponaztli, quijadas, etc.) and found objects (tin cans, brake drums, conch shells, etc.). This resulted with them being added to the conventional percussion instruments (bells, cymbals, tam-tams, etc.). However, the most important innovation was the prepared piano.