How did Nadia Boulanger's teaching style impact the development of distinctively American-sounding art music?

What will be an ideal response?

Unlike many teachers of composition who expected their students to emulate their personal styles, Boulanger directed each of her students to experiment with their own distinctive talents and compositional interests. She also encouraged her American students to seek out truly "American sounds," including jazz. For this reason, composers such as Aaron Copland produced works incorporating everything from jazz to Mexican and popular music. The stylistic differences in the compositions of Boulanger's students is evidenced in this chapter by comparing Aaron Copland's music to that of Samuel Barber.