Give a short summary of act one of the play our town

The play opens with a view of an empty, curtainless, half-lighted stage. The Stage Manager enters and arranges minimal scenery—a table and three chairs—to represent two houses, one on each side of the stage. The houselights dim as the Stage Manager moves about the stage. When the theater is completely dark, he introduces the play, naming the playwright, producers, director, and cast. He then identifies the setting: the town of Grover’s Corners, New Hampshire, just before dawn on May 7, 1901.

i'm not sure i completely understand your question, but i will do my best.

i think the answer you are looking for is sequence. (see below)

a repeated melodic fragment would be best defined as repetition, while repeated chords (different or the same) could be a chord progression. however, you then mentioned the chord and melodic fragment beginning on higher or lower pitches, in that case, the answer could be best defined as a sequence. the definition of a sequence is as follows: "the restatement of a motif or longer melodic (or harmonic) passage at a higher or lower pitch in the same voice."

let me know if this !