How to answer “purpose” questions on the ACT & SAT

One of the more common question types on the Reading sections of the ACT and SAT is that of “primary purpose” questions. There are two types of purpose questions on the ACT and SAT: those that reference the passage as a whole and those that reference a specific line or paragraph. There are similarities between the two types, but today we will focus on the more specific type of purpose question.

Usually, these questions will contain phrasing such as “the primary purpose of lines 25-31…” or “one of the main purposes of the final paragraph is…” From that perspective, these questions are easy to identify. Once you find yourself facing a purpose question, you want to ask yourself two things.

  • First, what is the author trying to accomplish with this information?
  • Second, what would the paragraph or sentence lose if this information were removed?


Let’s look at a very simple example to illustrate this point. Suppose you had the following sentence in an SAT Reading passage:

Despite her extensive training in theoretical physics, Felicia was confused by string theory.

Let’s talk about the purpose of the first half of the sentence, using the two questions I introduced above. While there are probably several equally legitimate responses in this case, my answer to the first question would be “the author is trying to provide context for the rest of the sentence.”

To the second question, I would say, “without the first part of the sentence, the rest of the sentence is not at all noteworthy.” Let’s consider what would happen if we deleted the first half of the sentence, leaving only “Felicia was confused by string theory.” Who cares? Almost everyone is confused by string theory. It’s only when we consider the second part of the sentence in the context of the first part that the sentence becomes more important and surprising.

Now let’s consider a longer section of a passage along with an ACT Reading question:

Although spanning less area than it did thousands of years ago, Bialowieza Forest covers 1,400 square kilometers in Poland and Belarus and is designated a UNESCO World Heritage Site. In this lush and verdant locale, European Bison hide behind leafy green shrubbery, and age-old oak trees line crystal clear streams. Naturalists visiting the forest gave its trees nicknames such as “The King of Nieznanowo” and “Emperor of the South” for their stately, royal appearance.

  • Question: The main purpose of the information in the second two sentences (“In this lush… royal appearance”) is to ...

Before we look at the answer choices, let’s answer the same two questions we answered before. What is the author trying to accomplish with this information? It seems to me that the author is trying to give us a description of some of the natural features that are present in Bialowieza Forest. What would the paragraph lose if this information were removed? It would lose a vivid and evocative illustration, leaving a bland set of facts that don’t adequately describe the forest.

Let’s now turn to the answer choices and find the one that best matches our answers to those two questions. If you're stuck, you can consider the tone and theme of the passage, eliminating options that don't fit.

(A) describe in scientific detail the different animals that naturalists encountered.
(B) depict Bialowieza Forest as a vibrant and majestic natural area.
(C) provide specific measurements that show the size of the forest.
(D) list all of the names that naturalists gave to trees.

As you can see, answer choice B fits with our characterization of the purpose of the information in the final two sentences.

Not only are purpose questions some of the most frequently-tested question types, but understanding the author’s reasons for including different pieces of information can be helpful for a variety of different questions. Use the two cues in this blog to help identify the author’s primary purpose in a particular paragraph or sentence. Good luck!

For more tips, download our guide to the 6 skills you need to master for the SAT and the 6 skills you need to master for the ACT.

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