Master the ACT Science Conflicting Viewpoints passage: compare two scientists' hypotheses, find where they agree and disagree, and match new evidence to the side it supports.
State each viewpoint's main claim in one sentence before the questions.
Everything else in an essay is support for that one claim.
Both usually agree on the OBSERVATION and disagree on its CAUSE.
A scientist may accept a fact as true yet reject it as the explanation.
A new finding supports the viewpoint whose claim it fits.
The same finding often weakens the rival, since the claims compete.
Reason only from that viewpoint's stated logic, not your own opinion.
Ask: does this statement follow from the scientist's core claim?
Every ACT Science section contains one Conflicting Viewpoints passage — the odd one out. Instead of tables and graphs, it presents two (sometimes three) short essays in which scientists or students defend rival explanations for the same phenomenon. The questions ask you to understand each position, locate where the positions clash, and judge what evidence would help or hurt each one. This is close reading, not calculation, but the discipline is the same: every answer comes from the text.
Before any detail, pin down each viewpoint's main claim in one sentence. Suppose a passage debates why a desert lake has been shrinking:
Scientist 1 argues the lake is shrinking mainly because of reduced rainfall. Over the past forty years the region's yearly rainfall has dropped, and less water flows into the lake than evaporates from it, so its level falls.
Scientist 2 argues the lake is shrinking mainly because of increased human water use. Farms upstream now divert river water for irrigation, so less river water reaches the lake; rainfall, Scientist 2 says, has changed too little to matter.
The core claims are: rainfall down (Scientist 1) vs. humans diverting water (Scientist 2). Everything else in each essay is support for its core claim. If you can state both claims in your own words, most questions become easy.
The ACT loves to ask what the two scientists agree on and where they disagree. They almost always agree on the basic observation and disagree on its cause:
Watch for a subtler pattern: a viewpoint may concede a fact but deny it is the main cause. Scientist 2 admits rainfall changed but calls the change too small to matter. So "rainfall has decreased" is something Scientist 2 might accept as a fact while still rejecting as the explanation. Precise reading separates "agrees the fact is true" from "agrees it is the cause."
The signature Conflicting Viewpoints question gives a new finding and asks whose view it strengthens (or weakens). The method: ask which claim the finding fits.
Notice that one finding can strengthen one scientist while weakening the other, because the two offer competing explanations for the same fact.
Another common stem: "Scientist 1 would most likely agree with which statement?" Answer it by staying inside that scientist's logic. Scientist 1 blames rainfall, so Scientist 1 would agree that "restoring the lake requires wetter years," and would disagree that "halting all upstream irrigation would refill the lake." You are role-playing each viewpoint, using only what its essay commits it to.
Handle the Conflicting Viewpoints passage as a structured debate, and its questions turn from intimidating to mechanical: find each thesis, map the clash, and route every new fact to the side it fits.
Scientist A: A nearby pond turns green each July because fertilizer runoff from farms feeds algae. Scientist B: The pond turns green each July because summer heat warms the water and lets naturally present algae bloom. On what do the two scientists disagree?
Using the pond passage above (Scientist A: fertilizer; Scientist B: summer heat), which statement would BOTH scientists most likely accept?
Pond passage (A: fertilizer runoff; B: summer heat). A researcher finds that in a nearby pond with no farms upstream, the water still turns green every July. Which viewpoint does this finding support?
Lake passage — Scientist 1: the lake shrinks because rainfall has dropped. Scientist 2: the lake shrinks because upstream farms divert its water. Which finding would most weaken Scientist 1?
Lake passage (Scientist 1: less rainfall; Scientist 2: upstream diversion). With which statement would Scientist 2 most likely AGREE?
In the lake passage, Scientist 2 writes: "Regional rainfall has indeed declined somewhat, but the decline is far too small to explain the lake's rapid retreat; upstream diversion is the real driver." A question asks: which statement is BOTH consistent with Scientist 2's essay AND something Scientist 1 relies on?
Blurring the two viewpoints together and losing track of which scientist made which claim.
Write each scientist's core claim in one sentence before reading the questions, then label every question with the name it asks about.
Assuming the scientists disagree about everything, including the basic observation.
They almost always share the observation and split on its cause. Identify the shared fact first — it is the answer to "both would agree" questions.
Treating a concession ("rainfall did fall somewhat") as full agreement with the rival's conclusion.
Distinguish accepting a fact from accepting it as the cause. A scientist can grant the fact while denying it is the main explanation.
Answering "which view does this support?" from your own opinion or outside science knowledge.
Match the new finding only to the claim it fits within the passage. If a required cause is absent yet the effect still happens, that supports the rival view.
Student 1: Meteorite X formed in the asteroid belt, because it contains minerals that need low pressure to crystallize. Student 2: Meteorite X formed deep inside a large planet, because its minerals show signs of forming under high pressure. On what do the two students most clearly disagree?
Scientist 1: A cave's temperature stays constant year-round because thick rock insulates it from outside air. Scientist 2: The cave stays constant because an underground stream carries away any heat that enters. Which statement would BOTH scientists most likely accept?
A forest's deer population has fallen sharply. Scientist 1 blames a new predator that moved into the area; Scientist 2 blames a disease spreading among the deer. Researchers then find that deer in a fenced area predators cannot enter died off just as fast. Which viewpoint does this finding support?
Scientist 1: A metal tool aged rapidly because salty coastal air corroded it. Scientist 2: It aged rapidly because it was repeatedly heated and cooled, cracking its surface. Which new finding would most weaken Scientist 1?
A town's river has grown murkier. Scientist 1: upstream construction is washing soil into it. Scientist 2: a bloom of tiny algae is clouding the water. With which statement would Scientist 2 most likely AGREE?
Scientist 2 writes: "The glacier has retreated partly because of a few warm summers, but that alone is minor; the main cause is that less snow now falls to replenish it." Which statement is BOTH consistent with Scientist 2's essay AND relied on by Scientist 1, who argues warming is the primary cause?
Test a model or prediction against ACT Science data: decide whether results support it, which data would strengthen or weaken it, and how to refine a model that partly fails.
Judge whether ACT Science data actually supports a stated conclusion, tell a supported claim from an overreach, and name the new evidence that would confirm a result.