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Learn to identify, compare, and evaluate competing scientific explanations on the ACT Science section.
Science rarely advances through a single, unanimous explanation. Instead, researchers propose competing hypotheses — testable explanations for the same phenomenon — and then gather evidence to determine which one best fits the data. The ACT Science section tests your ability to read passages where two or more scientists present different viewpoints and then answer questions that ask you to compare, contrast, and evaluate those positions. Understanding how this skill developed historically helps you see why it appears so prominently on the test.
The central question behind every Conflicting Viewpoints passage on the ACT is this: How do two or more explanations differ, what evidence supports each, and where do they agree or disagree? Mastering this skill not only raises your ACT Science score but also trains a habit of mind you will use throughout college and beyond.
Before you dive into practice passages, you need a solid framework for approaching any Conflicting Viewpoints question. The ACT Science section typically presents these passages with an introductory paragraph describing a phenomenon, followed by two to four labeled viewpoints (often called Scientist 1, Scientist 2, etc., or Hypothesis 1, Hypothesis 2, etc.). Each viewpoint offers a distinct explanation. Your job is to dissect each one systematically.
The diagram below shows the typical architecture of a Conflicting Viewpoints passage on the ACT Science section. Notice how a shared introduction sets the stage, and then each viewpoint branches off with its own claim, evidence, and predictions. Understanding this structure helps you read strategically — you can annotate each section as you go rather than trying to absorb everything at once.
When you first encounter a Conflicting Viewpoints passage, resist the urge to read every word in order from top to bottom. Instead, start by reading the introduction carefully because it gives you the shared context that both viewpoints build on. Then, for each viewpoint, identify the core claim in the first sentence or two and lightly mark the evidence and predictions. This active reading strategy lets you answer questions much faster because you already know where to look for specific information.
The ACT Science section includes seven passages, and typically one of them is a Conflicting Viewpoints passage. This passage is unique because it is the most text-heavy passage on the test — it relies less on graphs and tables and more on careful reading. The passage presents two or more positions, and the questions fall into several predictable categories. Understanding these categories is your strategic advantage.
Most students find that comparison questions and strengthening/weakening questions are the most challenging because they require you to hold both viewpoints in mind simultaneously. A helpful strategy is to create a quick mental (or written) T-chart as you read: jot the key difference between the two viewpoints in just a few words. For example, if Scientist 1 believes a lake was formed by a glacier and Scientist 2 believes it was formed by volcanic activity, your note might simply say "VP1 = glacier, VP2 = volcano." This anchors your thinking as you tackle the questions.
The most effective tool for comparing viewpoints on the ACT is the T-Chart Method. As you read each viewpoint, you fill in a simple two-column chart that captures the key dimensions of each argument. The diagram below illustrates this approach with a sample passage about two scientists debating the cause of mass extinction events.
When constructing your T-chart, keep your notes extremely brief — just a few key words per row. The purpose is not to rewrite the passage but to create a quick-reference map. The claim row is the most important because it captures the fundamental disagreement. If you can state each scientist's claim in one short phrase, you will be able to answer the majority of comparison questions without re-reading the passage.
Let's walk through a complete ACT-style question using the mass extinction passage from our T-chart. This demonstrates exactly how to use your annotations to select the correct answer efficiently.
The ACT is a well-crafted test, and the wrong answer choices in Conflicting Viewpoints questions are not random — they are designed to catch students who make predictable mistakes. Below is a comparison of common traps alongside the strategies that help you avoid them.
| Common Trap | What It Looks Like | How to Avoid It |
|---|---|---|
| Mixing up the viewpoints | An answer accurately describes Scientist 2's position, but the question asks about Scientist 1. | Always check which viewpoint the question refers to. Circle the scientist number in the question stem. |
| Extreme language | An answer uses words like "proves," "always," "never," or "completely disproves" when the evidence only suggests or supports. | Be wary of absolutes. Science is about evidence-based conclusions, not proof beyond all doubt. Prefer answers with measured language. |
| True but irrelevant | An answer is factually correct based on the passage but does not answer the specific question being asked. | Re-read the question after narrowing your choices. Ask: Does this answer what was specifically asked? |
| Outside knowledge bias | You pick the answer that matches what you learned in biology class, even though the passage says something different. | Base every answer on what the passage states, not on your prior knowledge. The ACT tests reading comprehension, not content mastery. |
| Confusing agreement with disagreement | A question asks where both agree, but you pick a point of disagreement (or vice versa). | Use the bottom row of your T-chart (shared facts). If both viewpoints accept a fact, that is agreement; if they interpret it differently, that is disagreement. |
The skill of comparing viewpoints is not just a test-taking strategy — it is the foundation of scientific literacy. In college-level science courses, peer-reviewed research papers often present competing models that must be evaluated with the same toolkit you are developing now. The table below shows how the ACT version of this skill connects to its more advanced counterpart.
| Dimension | ACT Conflicting Viewpoints | College-Level Scientific Evaluation |
|---|---|---|
| Format | Two to four viewpoints, clearly labeled | Multiple published studies with nuanced, overlapping positions |
| Evidence Source | Provided within the passage | Must locate through literature review and experimentation |
| Evaluation | Determine which viewpoint new evidence supports | Design experiments to test hypotheses and analyze statistical significance |
| Scope | Identify agreement and disagreement | Synthesize competing models into unified frameworks |
| Core Skill | Reading comprehension + logical reasoning | Critical analysis + experimental design + statistical reasoning |
When you practice comparing viewpoints for the ACT, you are building a mental muscle that will serve you in college-level biology, chemistry, physics, psychology, and even subjects like economics and political science. Everywhere experts disagree, the ability to identify what they disagree about, what evidence each side presents, and what new evidence would settle the debate is invaluable.
Use the following scenario for all five questions. Read it carefully and, if you like, sketch a quick T-chart before tackling the questions.