Reading Data in Tables and Graphs
Answer ACT Science questions by reading trends directly from tables and graphs — no outside science knowledge required.
Introduction
Most ACT Science questions can be answered using only the data given in a table or graph. The section tests whether you can read a trend accurately, not whether you remember biology or chemistry facts.
Theory
Start by identifying what each axis or column represents and its units. Then look for a trend: does one variable increase, decrease, or stay the same as another changes?
When a question asks you to predict a value NOT directly shown in the data, look at the existing trend and extend it logically (interpolate between two given points, or extrapolate slightly beyond them) — do not guess randomly.
When a question asks WHY an experiment was designed a certain way, look for what stayed constant across groups (the "controlled variables") — that is usually the basis for the answer.
Examples
Example: A table shows reaction time (seconds) at three temperatures: 10 degrees C = 12 sec, 20 degrees C = 8 sec, 30 degrees C = 5 sec. The trend: reaction time decreases as temperature increases. If asked to predict the value at 25 degrees C, expect a number between 5 and 8 seconds, since 25 falls between 20 and 30.
Practice
Check your understanding 1
A graph shows that as pressure increases from 1 to 4 atm, gas volume decreases from 20 to 5 liters. What would you predict happens to volume if pressure increases further to 6 atm?
Check your understanding 2
In an experiment testing fertilizer amount on plant growth, all plants get the same water, soil, and light, but different fertilizer amounts. Why keep water, soil, and light the same across groups?
Common mistakes
Bringing in outside knowledge instead of reading the actual data given — the ACT Science section is designed so the answer is always traceable to the table, graph, or passage in front of you.
Where to go next
Practise this: drills for this topic in the question bank.