How to read values, units, and axes off ACT Science tables and graphs — and how to pull a single fact out of a busy figure without needing any outside science knowledge.
Name each axis/column and its UNITS before reading any value.
Most wrong answers are a right number in the wrong units or wrong column.
Given value → across to curve/row → down to the other axis.
On a graph, confirm which axis you are given BEFORE moving.
When a question spans two tables, chain them through the shared column.
The linking variable (e.g., "Sample" or "Temperature") is your path.
Given a result, find where the data reaches it, then read the input.
Use for "at which value is Y closest to ___?" questions.
The largest share of ACT Science points comes from "Data Representation" — passages built around graphs, tables, and diagrams. The reassuring truth is that these questions almost never require you to know science. They require you to read science: to find the row, the column, the axis, or the point that answers the exact question asked. Students lose these points not because the biology or physics is hard, but because they misread a unit, grab the wrong column, or answer a question the figure never asked.
Treat every figure as a lookup table. Your job is to locate one value, or to compare two values the passage puts side by side. That is it.
Before touching the choices, spend ten seconds mapping the figure:
Suppose a study reports the solubility of a compound at different temperatures.
| Temperature (°C) | Solubility (g per 100 mL water) |
|---|---|
| 10 | 21 |
| 20 | 34 |
| 30 | 46 |
| 40 | 55 |
| 50 | 61 |
To answer "What is the solubility at ?", you do not calculate anything. You find the row where Temperature and read across: g per 100 mL. That is the whole skill. The ACT dresses it up — "A chemist dissolves the maximum possible amount of the compound in 100 mL of water held at . What mass dissolves?" — but the answer is still the number in that cell: g.
Data Representation passages frequently ask you to combine two displays. Consider a second table from the same study:
| Sample | Temperature (°C) |
|---|---|
| P | 20 |
| Q | 40 |
| R | 10 |
If a question asks "What is the solubility of the water in Sample Q?", you chain the two tables: Sample Q is at (Table 2), and corresponds to g per 100 mL (Table 1). Neither table alone answers the question; the link is the shared "Temperature" column. Whenever a question names something that appears in one figure but asks for a quantity in another, look for the shared variable that bridges them.
A line or scatter graph is a table with the numbers erased and replaced by position. To read a value, find the given value on one axis, move straight across (or up) to the curve or point, then drop to the other axis. The two classic misreads:
Harder Data Representation items layer a condition onto the lookup: "According to Figure 1, at which temperature is solubility closest to g per 100 mL?" Here you run the lookup backward — start from the value in the answer ( g), find where the curve or column reaches it, and read the matching temperature. In the table above, g sits between ( g, g too high) and ( g, only g too low) — compare the gap on each side, and since , is closest. You are still only reading the table — just entering from the other side.
Before you commit, reread the stem and ask: "Did I answer the exact quantity requested, in the exact units printed on the choices?" Most wrong answers on Data Representation are right numbers pulled from the wrong row, the wrong figure, or the wrong units. The science is never the obstacle. The careful reading is the skill.
Table 1 shows the boiling point of a saltwater solution at different salt concentrations.
| Salt added (g per L) | Boiling point (°C) |
|---|---|
| 0 | 100.0 |
| 20 | 100.6 |
| 40 | 101.1 |
| 60 | 101.7 |
According to Table 1, what is the boiling point when 40 g of salt is added per liter?
A graph plots a cart's distance traveled (in meters) against time (in minutes). At 3 minutes the curve reads 180 m. A question asks: what was the distance in meters at 180 seconds?
Table 1 gives the density of four liquids. Table 2 assigns each liquid to a beaker.
Table 1
| Liquid | Density (g per mL) |
|---|---|
| W | 0.79 |
| X | 1.00 |
| Y | 1.26 |
| Z | 0.92 |
Table 2
| Beaker | Liquid |
|---|---|
| 1 | Y |
| 2 | W |
| 3 | Z |
What is the density of the liquid in Beaker 2?
Table 1 shows how far light penetrates ocean water of varying clarity.
| Water clarity index | Light depth (m) |
|---|---|
| 1 | 12 |
| 2 | 25 |
| 3 | 41 |
| 4 | 58 |
| 5 | 70 |
At which clarity index does light reach a depth closest to 50 m?
Table 1: reaction rate vs. temperature. Table 2: the temperature of three trials. A note states that a reaction is "usable" only if its rate exceeds 30 units per minute.
Table 1
| Temperature (°C) | Rate (units per min) |
|---|---|
| 25 | 14 |
| 35 | 22 |
| 45 | 33 |
| 55 | 48 |
Table 2
| Trial | Temperature (°C) |
|---|---|
| A | 35 |
| B | 45 |
| C | 25 |
Which trials produced a "usable" reaction?
A graph plots bacterial population (y-axis) against hours (x-axis). The y-axis is labeled at 0, 100, 1,000, and 10,000 — each equal step up the axis multiplies the value by 10 (a log scale). A point sits exactly halfway between the "1,000" and "10,000" gridlines. A student reads the population as 5,500. Is that correct?
Grabbing the right number from the wrong column or the wrong figure. Busy passages put several similar-looking values near each other.
Put your finger on the exact row/column named in the stem and read straight across. If the value comes from a second figure, name the shared variable that links them first.
Answering in the units printed on the figure when the question (or the choices) uses different units — minutes vs. seconds, grams vs. kilograms.
Circle the units in the stem and in the axis label. If they differ, the conversion is part of the question, not an afterthought.
Assuming a graph's axis is linear. Some ACT figures use log or unevenly spaced scales, so counting boxes gives the wrong value.
Read the printed numbers on the axis, not the number of gridlines. If equal steps multiply the value, the axis is logarithmic and positions cannot be averaged.
Bringing in outside science knowledge to "correct" the data. Data Representation questions are answered entirely from the figure, even if a real-world fact seems to contradict it.
Trust the printed data. If the table says solubility rises with temperature, that is the answer for this passage — the ACT rewards reading the figure, not recalling a textbook.
Table 1 shows the mass of water vapor a kilogram of air can hold at different temperatures.
| Temperature (°C) | Max water vapor (g per kg air) |
|---|---|
| 5 | 5.4 |
| 15 | 10.6 |
| 25 | 20.0 |
| 35 | 37.3 |
According to Table 1, what is the maximum water vapor a kilogram of air can hold at 25 °C?
A graph plots a plant's height in centimeters (y-axis) against its age in weeks (x-axis). The curve passes through (2, 6), (4, 15), and (6, 27). A question asks for the plant's height, in centimeters, at an age of 28 days.
Table 1 gives the melting point of four metals. Table 2 assigns each metal to a labeled ingot.
Table 1
| Metal | Melting point (°C) |
|---|---|
| Tin | 232 |
| Lead | 327 |
| Zinc | 420 |
| Silver | 962 |
Table 2
| Ingot | Metal |
|---|---|
| I | Zinc |
| II | Tin |
| III | Silver |
What is the melting point of the metal in Ingot III?
Table 1 shows the pressure inside a sealed container as it is heated.
| Temperature (K) | Pressure (kPa) |
|---|---|
| 250 | 83 |
| 300 | 100 |
| 350 | 116 |
| 400 | 133 |
| 450 | 149 |
At which temperature is the pressure closest to 125 kPa?
Table 1 lists the energy output of a solar panel at several light levels. Table 2 records the light level during three tests. The panel is rated "efficient" only when its output exceeds 40 W.
Table 1
| Light level (lux) | Output (W) |
|---|---|
| 200 | 18 |
| 400 | 35 |
| 600 | 44 |
| 800 | 52 |
Table 2
| Test | Light level (lux) |
|---|---|
| J | 400 |
| K | 600 |
| L | 800 |
Based on the tables, in which tests was the panel "efficient"?
A graph plots the number of radioactive atoms remaining (y-axis) against time. The y-axis is labeled 10, 100, 1,000, and 10,000, and each equal vertical step multiplies the value by 10. A data point sits exactly halfway between the "100" and "1,000" gridlines. Which value does that point represent?
Spot direct and inverse trends in ACT Science data, describe how two variables relate, and interpolate or extrapolate a value beyond the rows the table gives you.
Identify independent, dependent, and controlled variables in an ACT Research Summary, spot the control group, and explain why an experimental step was included — all from the passage.