rig•ma•role - Pronunciation: (rig'mu-rOl), [key] 
—n. 
1. an elaborate or complicated procedure: to go through the rigmarole of a formal dinner. 
2. confused, incoherent, foolish, or meaningless talk. Also,rigamarole.

SCHOOL : HOMEWORK :: orchestra :violin

The best answer is violin. The relationship between the first pair of words, school and homework, is that of part to whole—one word is a part or piece of the other. Therefore, the second pair of words must also have a part-to-whole relationship. A violin is part of an orchestra.