Question 27·Hard·Text Structure and Purpose
Popular writers often turn to familiar household devices when explaining complex scientific systems, but the results are not always illuminating. A recent article, for example, likened Earth’s climate to a thermostat that clicks on when temperatures rise and shuts off when they fall, implying an automatic mechanism that quickly restores balance. The analogy is catchy, yet it conceals more than it reveals: thermostats respond instantly and predictably, whereas climate feedbacks can be sluggish, nonlinear, and sometimes amplifying rather than dampening. By overlooking these distinctions, the article risks encouraging readers to expect swift, orderly corrections to any temperature change—an expectation at odds with the decades-long lags and potential tipping points documented by climatologists.
Which choice best describes the primary purpose of the passage?
For primary-purpose questions, first read (or reread) the first and last sentences carefully, because they usually frame the main point and the consequence or takeaway. In one short sentence, summarize what the author is “doing” (for example: criticizing a comparison, explaining a process, proposing a solution). Then test each answer choice against that summary, watching for choices that introduce things the passage never does, such as giving a history, proposing a detailed solution, or summarizing research. Eliminate any option that adds new goals or topics not clearly supported by the whole passage, and choose the one that best matches both the author’s action and scope.
Hints
Use the beginning and the end of the passage
Reread the first and last sentences. What problem does the author introduce at the beginning, and what risk or consequence is highlighted at the end?
Focus on what the author is doing, not just what they mention
Ask yourself: Is the author mainly describing how climate works, proposing a new idea, telling a history, or criticizing something about how climate is explained?
Check for things that never happen in the passage
Look at each answer choice and ask: Does the passage actually give a new metaphor, discuss multiple time periods, or talk about engineering research? Eliminate any answers that require information or purposes that are simply not in the passage.
Pay attention to the effect on readers
In the final sentence, what does the author say the article "risks encouraging" in readers? How does that help you understand the author’s overall aim?
Step-by-step Explanation
Identify the general topic and tone
Read the first sentence: it notes that writers use household devices to explain science, but says the results are “not always illuminating.” This establishes a critical stance toward these kinds of analogies. The passage then develops one example: comparing Earth’s climate to a thermostat.
Find the author’s main point
The author says the analogy is “catchy, yet it conceals more than it reveals” and then highlights why: thermostats respond instantly and predictably, but climate feedbacks can be sluggish, nonlinear, and even amplifying. The final sentence emphasizes the risk to readers’ expectations (expecting swift, orderly corrections) and says that expectation conflicts with scientific evidence (lags and tipping points).
Match the scope of the passage to the choices
The passage is not just listing facts about climate; it is criticizing the use of a familiar metaphor because it can give readers the wrong impression. Eliminate choices that claim the author proposes a replacement metaphor or that reduce the purpose to only one detail (only climate mechanics or only the consequence).
Select the best answer
Because the author’s overarching purpose is to warn that a catchy household-device analogy can oversimplify climate dynamics and mislead readers, the best answer is To warn that seemingly straightforward analogies, such as the thermostat comparison, can oversimplify and distort public understanding of climate dynamics.