What is the purpose of an index in an informative essay?

What is the central idea in this advice from branch rickey to jackie robinson?  

Create three sentences describing a chore, each using comparison forms for these irregular words. good bad

Which of the following did shakespeare change in his version of romeo and juliet? he increased emphasis on the capulet-montague conflict. he made romeo and mercutio’s relationship more complicated. he made the franciscan friars more evil. he gave tybalt a smaller role.