ACT Reading — natural science, and how sure the writer actually is

The natural science passages on ACT Reading are the ones most often misread by people who know some science, because the questions are not about the science. They are about this particular article: what it says, in what order, and how sure it claims to be. A statement can be perfectly true about the world and the wrong answer about the page.

Ten questions on four invented articles — a fungus that dissolves limestone to feed, an atmospheric glow, a salmon that navigates by magnetism, and a basalt plain of hexagonal columns. Each question quotes its article in full, and no article carries more than three questions. Nothing here requires prior knowledge: everything needed is in the sentences.

Two questions ask for a technical term, and neither can be answered from memory. "Subterranean" is never defined, but the fungus lives in deep caverns and spreads through rock, and what those have in common is being underground; the wrong options each take a different real quality of the same place — its limestone, its moisture, its poverty in nutrients — and attach it to the word instead. "Lateral line" is settled by a single preposition: the fish carry crystals IN it, so it must be a part of the fish rather than a route or a magnetic field.

Two ask for the order of a process, and both turn on dependency rather than on the order the sentences happen to appear in: the enzyme must exist before the rock it dissolves, and the lava must flow before it can cool.

Two ask what the article states, with every wrong option present on the page and fastened to the wrong thing — altitude belongs to the ice crystals, winter stability to how often the glow appears, twilight to when it happens at all, and only dust concentration to its intensity.

The last two are the reason to work through this material. One article shifts its level of confidence three times in four sentences: it says flatly what the glow "occurs when", reports what one researcher "suggests" and then "maintains" against people who argue otherwise, and finally hedges a seasonal pattern with "appears to be". Reading those verbs is a skill in itself, and an option that turns a hedge into a settled fact is wrong no matter how likely the claim may be.

Twelve flashcards carry the method: recovering a definition from context, following a chain of steps, telling an observation from the explanation offered for it, and the words that mark how far a writer is willing to go.

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• Recover the meaning of a technical term from the sentences around it, without prior knowledge
• Put the steps of a described process in order by asking what each step depends on
• Keep track of what each fact in a passage is fastened to, not merely that it appears
• Tell a settled claim from a leading explanation and from an open question, by reading the writer's verbs
• Reject an option that turns a hedged claim into a certainty
• Reject an option that is scientifically plausible but says more than the passage does

Written for the natural-science strand of ACT Reading, following the skills the test's own published description names: central ideas, supporting details, sequential and cause-effect relationships, the meaning of words and phrases in context, and differentiating between what a text presents as fact and what it presents as an interpretation. This is reading rather than data analysis: there are no tables, graphs or experiments to compare, which is the work of the Science section and of the materials in that category. Every species, site, observatory, researcher and study named here is invented for this material, and nothing is taken from any ACT publication or released test.