Aaron Copland was an American composer, composition teacher, writer and conductor, who developed a distinctive musical style of composition which included American themes.
Copland's father had no musical preoccupations, but fortunately, his mother sang and played the piano. She arranged for her children to receive music lessons. Among his siblings, his oldest brother Ralph was the most advanced musically, proficient on the violin. He developed a strong connection with his sister, Laurine, who gave little Aaron his first piano lessons, promoted his musical education and furthermore, supported his musical career.
At the age of 11, Copland devised an opera scenario he called Zenatello, which included 7 bars of music, his very first notated music. By the age of 15, after attending a concert by composer-pianist Ignacy Jan Paderewski, he decided to become a composer. He started studying harmony through a correspondence course, and although the environment wasn't appropriate, he struggled toward his goal. He then continued his studies in harmony, theory, and composition under the noted teacher and composer of American music Rubin Goldmark. Copland's graduation piece from his studies with Goldmark was a three-movement piano sonata in a Romantic style. But he had also composed more original and daring pieces which he did not share with his teacher.
After graduating from high school, Copland played for a while in dance bands. Continuing his musical education, he received further piano lessons from Victor Wittgenstein, who found his student to be "quiet, shy, well-mannered, and gracious in accepting criticism." In the 1917-1921 period, Copland's compositions were juvenile works of short piano pieces and art songs. In the summer of 1921 Copland attended the newly founded school for Americans at Fontainebleau, Paris, where he came under the influence of Nadia Boulanger, a brilliant teacher who shaped the outlook of an entire generation of American musicians.
After spending 3 years in Paris he returned to New York to write an organ concerto, commissioned by Nadia Boulanger for her American appearances. While working as a pianist in a hotel trio at a summer resort in Pennsylvania, he composed the piece. Later that season, his Symphony for Organ and Orchestra was premiered at Carnegie Hall with the New York Symphony under the direction of the composer and conductor Walter Damrosch.
After he returned to the U.S., determined to follow his plans to become a full-time composer, rented a studio apartment on New York city's Upper West Side in the Empire Hotel. This kept him close to Carnegie Hall and other musical venues and publishers. In his pursuit to become a full-time composer, Copland mirrored the important trends of his time. He began working with jazz rhythms in Music for the Theater (1925) and the Piano Concerto (1926).
There followed a period during which he was strongly influenced by Igor Stravinsky’s Neoclassicism, turning toward an abstract style he described as “more spare in sonority, more lean in texture.” This outlook prevailed in the Piano Variations (1930), Short Symphony (1933), and Statements for Orchestra (1933–35). After this last work, there occurred a change of direction that was to usher in the most productive phase of Copland’s career.
Perhaps motivated by the plight of children during the Depression, around 1935 Copland began to compose musical pieces for young audiences, in accordance with the first goal of American Gebrauchsmusik. These works included piano pieces (The Young Pioneers) and an opera (The Second Hurricane). During this period he traveled extensively to Europe, Africa, and Mexico, where he became friends with the Mexican composer Carlos Chávez.
The decade that followed saw the production of the scores that spread Copland’s fame throughout the world. Most important of these were the three ballets based on American folk material: Billy the Kid (1938), Rodeo (1942), and Appalachian Spring (1944; commissioned by dancer Martha Graham). To this group belong also El salón México (1936), an orchestral piece based on Mexican melodies and rhythms; two works for high-school students—the “play opera” The Second Hurricane (1937) and An Outdoor Overture (1938); and a series of film scores, of which the best known are Of Mice and Men (1939), Our Town (1940), The Red Pony (1948), and The Heiress(1948). Typical too of the Copland style are two major works that were written in time of war—Lincoln Portrait (1942), for speaker and chorus, on a text drawn from Lincoln’s speeches, and Letter from Home (1944), as well as the melodious Third Symphony (1946).
In 1950, after receiving a scholarship to study in Rome, Copland composed his Piano Quartet which adopted Schoenberg's twelve-tone method of composition, and Old American Songs (1950). During the 1950s and early 1960s he traveled extensively and got acquainted with the avant-garde styles of Europe, the new school of Soviet music and the works of Toru Takemitsu, which later became his friend. His later works include an opera, The Tender Land (1954); Twelve Poems of Emily Dickinson (1950), for voice and piano; and the delightful Nonet (1960). Noted among his works which included Schoenberg's twelve-tone composition method are Piano Fantasy (1957), Connotations (1962) and Inscape (1967). The 12-tone works were not generally well-received; after 1970 Copland virtually stopped composing, though he continued to lecture and to conduct through the mid-1980s.
For the better part of four decades, as composer (of operas, ballets, orchestral music, band music, chamber music, choral music, and film scores), teacher, writer of books and articles on music, organizer of musical events, and a much sought after conductor, Copland expressed “the deepest reactions of the American consciousness to the American scene.” He received more than 30 honorary degrees and many additional awards. His books include What to Listen for in Music (1939), Music and Imagination (1952), Copland on Music (1960), and The New Music, 1900–60 (1968). With the aid of Vivian Perlis, he wrote a two-volume autobiography (Copland: 1900 Through 1942  and Copland: Since 1943 ).
Here you can find a list of compositions by Aaron Copland.