December 15, 2018

How to Prepare for the Science Portion of the ACT


The ACT science section can be intimidating, especially for those who don’t consider themselves strong in science.  The best way to prepare is to learn the types of passages and questions that you're likely to encounter by practicing questions modeled after the actual exam.

ACT Science Passages

Each exam has 6-7 passages with approximately 6-7 questions per passage.  The types of passages that may be on a single test generally include:

  • A comparison of students' or scientists' viewpoints on scientific topics
  • Experiments or studies with graphs and tables displaying the results
  • Scientific content in the areas of biology, chemistry, physics, and Earth/space science

Question Categorization

The ACT science section contains 40 questions and lasts 35 minutes.  These 40 questions can be divided into 3 categories:

  • Interpretation of data–reading and understanding figures, tables, and graphs (approximately 45% of the test)
  • Scientific investigation–understanding the purpose of an experiment or a particular part of the experiment (approximately 25% of the test)
  • Evaluation of models, inferences, and experimental results–interpreting explanations, discussions, and viewpoints made by scientists or students (approximately 30% of the test)

ACT Science Prior Knowledge

Although the passages provide most of the information required to answer the questions, the ACT science portion requires basic scientific skills and an understanding of science that may not be given in the passages.  For example, the ability to read and interpret graphs and tables is critical to obtaining a good score, but obtaining a great score may require an understanding of the difference between speed and momentum.  Questions that require prior knowledge (understanding of concepts not included in the passages) can be classified in the following ways:

Science skills in general

The question is from ACT released exam 2015-2016 Q17

  • Translating information from a table to a graph (as above)
  • Finding data trends in graphs/tables, such as increasing, decreasing, or no trend
  • Identifying independent variables, dependent variables, controlled variables, and constants within an experiment
  • Determining the tools used to obtain measurements in an experiment such as a balance, graduated cylinder, ruler, etc.
  • Identifying the chronological sequence of steps followed in an experiment
  • Converting values using the metric system, such as meters to millimeters or vice versa
  • Determining scientifically accurate viewpoints


The question is from ACT released exam 2010-2011 Q20

  • Determining the function of eukaryotic cell structures of both plants and animals (as above)
  • Understanding that osmosis is the diffusion of water through a semipermeable membrane
  • Knowing that cells use ATP as their source of energy
  • Understanding concepts and terminology in genetics (heterozygous vs. homozygous; genotype vs. phenotype)
  • Determining if organisms are in the same genus, species, kingdoms, etc.
  • Knowing the basic structure and function of biological molecules such as carbohydrates, proteins, lipids, and nucleic acids


The question is from released ACT exam 2018-2019 Q13

  • Understanding concepts related to density, including the formula for density (as above)
  • Knowing the properties of solids, liquids, and gases
  • Finding the atomic mass of a substance on a periodic table
  • Balancing and understanding chemical equations (reactants, products, and byproducts)
  • Understanding the pH scale, acids, and bases


The question is from released ACT exam 2015-2016 Q21

  • Knowing the direction of frictional force in relation to other forces (ex. gravity, drag, buoyancy)
  • Knowing the relationship between speed, momentum, velocity, and mass
  • Determining when gravitational potential energy is the greatest
  • Knowing the difference between potential and kinetic energy


The question is from released ACT exam 2018-2019 Q40

  • Determining formulas (expressions) used to obtain data shown in graphs/tables (as above)
  • Using basic multiplication and division
  • Calculating percentages and volumes
  • Reducing fractions
  • Extrapolating (determining a value outside the range of a table or graph)
  • Interpolating (determining a value between two numbers in a table or graph)
  • Determining how many times greater one data point is than another data point
  • Knowing the slope of a line can be positive, negative, or zero

Now that you know what types of passages and questions to expect, it's time to practice reading passages and start answering questions!

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