ACT Reading: Natural Science Strategy

Natural Science passages explain a process, mechanism, or phenomenon, how a biological system works, what a study found, why a natural event happens. This is not the ACT Science section: it's a reading passage, and everything you need to answer the questions is in the text itself. No outside science knowledge is required.

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Did you know

Natural Science passages are usually the most literal of the four types, less interpretation, more direct explanation. That makes them, for a lot of students, the fastest passage in the section once you get comfortable with how process-and-mechanism writing is structured.

What's tested

Three question types show up constantly. Each one below has the quick version, plus a "Learn more" with the specific strategy.

Process and sequence

Questions about the order of steps in a described process or mechanism, what happens first, what triggers what.

Learn more: mapping the sequence as you read

As you read a process description, mentally note the order of steps, or lightly number them if it helps. Sequence questions are common and reward having a clear map rather than a general impression.
Watch for sequence words: "first," "then," "after," "once," "subsequently." They're direct signals for order questions, and skipping past them is the most common way to get a step wrong.
A step description doesn't have to be adjacent to another to relate to it. The passage might describe step one, discuss related background, then return to step two several paragraphs later, don't assume proximity in the text always matches sequence.

Cause and effect within a system

What causes a described outcome, and how changing one variable in a system affects another.

Learn more: tracing the chain, one link at a time

Trace the causal chain one link at a time rather than jumping from the first cause straight to the final effect. Natural Science passages often describe multi-step chains, and skipping an intermediate step is a common source of errors.
"If X increases, what happens to Y" questions are asking you to follow the passage's own described relationship, not to reason from outside scientific knowledge. The answer is in the text, even when the underlying science also happens to be common knowledge.
Watch for indirect relationships. The passage might describe X affecting Y, which in turn affects Z, a question about X and Z requires following both links, not assuming a direct connection between them.

Scientific terminology in context

What a technical term means, based on how the passage defines or uses it, not on outside knowledge you're expected to already have.

Learn more: the passage always defines what it needs you to know

Every term you need to answer a question is defined or made clear somewhere in the passage. If a term feels unfamiliar, look for its definition or explanation nearby rather than relying on outside knowledge, which you're never required to have.
Watch for terms that sound like everyday words but are given a specific technical meaning in the passage. Use the passage's definition, even if it's narrower or different from the word's common usage.
If a question asks what a term "refers to" in the passage, that's a direct textual question, go find the sentence that introduces or explains the term rather than guessing from general familiarity with the word.

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Gotcha

Here's the classic trap, almost word for word how it shows up: a passage explains a specific mechanism, and an answer choice describes something that's scientifically accurate in the real world but isn't actually what this particular passage said. Students with outside science background sometimes answer from what they already know rather than from what the passage specifically states, and the ACT occasionally simplifies or frames a mechanism in a way that doesn't perfectly match the full scientific picture. Always answer from the passage's own explanation, even when your outside knowledge disagrees or adds more detail.

A quick sanity check before you lock in an answer

Ask whether your answer is something the passage actually says, versus something you know to be generally true about the topic. On this passage type especially, outside knowledge that isn't backed by the specific text in front of you is the most common source of a wrong answer.

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Quick tip

If a Natural Science passage describes a multi-step process, a quick mental (or scratch-paper) list of the steps in order takes seconds and pays off on any sequence or cause-and-effect question that follows.

Reading about the patterns is step one.

Ember has original Natural Science passages and questions, each with the reasoning explained the same way, including exactly which line supports the answer.

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