Homework was work assigned by a teacher to a student at a school. Such work was usually assigned to supplement classroom instruction. It was to be accomplished on the student's own time, usually at their home or residence. Failing to complete the homework would usually result in no grade.
Nog once failed to complete an essay about ethics for a class taught by Keiko O'Brien, but he escaped serious punishment by taking advantage of the substitute teacher, her husband Miles. He also asked to be excused from a gathering of Ferengi to do his homework. (DS9: "The Nagus")
While doing homework, Jake Sisko's imagination of Buck Bokai became reality. Bokai tried to win Jake for a baseball game but Jake refused and concentrated back on his homework. (DS9: "If Wishes Were Horses")