ACT Science Study Guide

The section is built from a series of passages, each presenting science material in one of three formats. Data Representation passages give you graphs, tables, and figures to read. Research Summaries describe one or more experiments and their setups. Conflicting Viewpoints passages present two or more competing hypotheses or explanations of the same phenomenon, and ask you to compare them.

Crucially, you are not expected to have memorized biology, chemistry, or physics facts. The passages draw on many science topics, but the questions are about what the data and the descriptions show — reading a trend off a graph, finding where two variables are equal, predicting the next value, identifying the variable an experiment changed, or pinning down what each viewpoint claims. A little background helps you read faster, but the answers live in the figures and text in front of you.

The ACT reports Science in three categories. The exam does not publish a fixed year-to-year percentage you can rely on, but the practical balance looks like this:

• Interpretation of Data — the largest share: reading graphs and tables, finding trends and relationships, interpolating and extrapolating, and translating between figures.
• Scientific Investigation — understanding experimental design: variables and controls, procedures, and how a setup would change if a condition were altered.
• Evaluation of Models, Inferences, and Experimental Results — the most analytical: judging whether data support a conclusion or hypothesis, and comparing competing explanations (the Conflicting Viewpoints passage lives largely here).

The takeaway: most of the section is data interpretation, so the single highest-value skill is reading figures quickly and exactly — axes, units, and the direction of each trend. Investigation and Evaluation reward understanding why an experiment was built a certain way and whether its results actually back the claim.

ACT Science rewards fast, literal figure-reading. A routine that works:

1. Go to the figures first. For Data Representation and Research Summaries, read the question, then go straight to the relevant graph or table — you rarely need to read the prose top to bottom.
2. Read axes, units, and labels before trends. Most data errors come from misreading a scale, an axis, or which line is which, not from faulty reasoning.
3. Practice describing trends out loud. "As X increases, Y decreases" is the core move; being able to state the relationship instantly makes most questions trivial.
4. Slow down only for Conflicting Viewpoints. That passage actually requires careful reading — nail down what each scientist claims and where they disagree before answering.
5. Drill with a clock, then review. The section is time-pressured, so build speed under timing, but study your misses to learn which figure or detail you overlooked.

• Reading the wrong axis, scale, or data series — a careless figure-read, not a reasoning failure, is the most common cause of lost points.
• Trying to use outside science knowledge instead of the data on the page, and choosing an answer that is "true" but unsupported by the passage.
• Over-reading the passages and burning time you needed for the figures and questions.
• Confusing the variables in an experiment — mixing up what was changed, what was measured, and what was held constant.
• On Conflicting Viewpoints, blending the positions together instead of tracking each one separately.
• Leaving blanks — there is no penalty for guessing, so answer every question even when time runs short.

Every reporting category below has a focused practice set with full written explanations and a rationale for every wrong choice, plus a worked-solutions page you can read straight through. Start with Interpretation of Data since it is the largest bucket and the fastest to improve, then take a mixed set across the whole section to rehearse moving between figures, experiment setups, and competing viewpoints under time pressure. It is free and needs no account.