What is the meaning behind "to kill a mocking bird"

Has anyone ever read the poem “at a window “ by carl sandburg? there are a few multiple choice questions i have to answer about it.

You're playing the slots and "win" twenty-five bucks! you're stoked. during the past ten weeks, you've won another fifty bucks. but you've dropped two bucks in the slot machines every day for ten weeks

Read each of the following statements and place a checkmark next to each true statement: test-makers give away answers to questions in other questions. a test-taker should check every 20 answers or so to make sure the questions and answers match. long passages on tests should be read quickly to save time. words like best, least, and worst require the test-taker to make judgments about the correct answer. test-takers should not try to answer the questions in their minds before reading over the answer choices. test-makers use the same letter three or four times in a row to trick test-takers.