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Reading Scientific Texts, Tables, Graphs and Diagrams

Learn to pull exact information out of science passages, tables, graphs and diagrams, and to translate between them.

Practice this skill 20 min Comprehending scientific presentations Leer en español
Key idea

What you'll learn

Almost every question on the GED Science test starts with a stimulus: a short passage, a table, a graph, a diagram, or a mix of these. Before you can reason about science, you have to read these presentations accurately. That skill is called comprehending scientific presentations, and it is the foundation for everything else on the test.

In this lesson you will learn to:

  • find the main idea and key details in a short science text;
  • read tables, including column headings and units;
  • read line graphs, bar graphs and scatter plots, including graphs with two y-axes;
  • understand diagrams and models such as food webs and cycles;
  • translate information from one form to another (for example, choose the sentence that matches a graph, or the table that matches a chart).

How it shows up on the GED: You do not need to memorize lots of science facts for these questions. The answer is in front of you. Typical wording includes "According to the graph…", "Based on the table…", "Which statement best describes the diagram?" and "Which table correctly shows the data?" Expect many questions on every Science test that depend on reading a figure.

Words to know

Key terms

  • stimulus — the passage, table, graph or diagram a question is based on (a graph of plant height over time).
  • table — data organized in rows and columns (one row per animal, one column per measurement).
  • column heading — the label at the top of a column; it tells you what is measured and the unit ("Mass (kg)").
  • unit — what a number is measured in (kg, °C, mg/L, beats per minute).
  • x-axis — the horizontal axis of a graph; usually shows the variable that was changed or time.
  • y-axis — the vertical axis; usually shows what was measured.
  • scale — how much each gridline or tick mark stands for (each gridline = 2 mg/L).
  • legend (key) — the box that tells you what each color, symbol or line means.
  • data point — one measured value plotted on a graph (a dot at 20 °C, 9.1 mg/L).
  • trend — the overall direction of the data (rising, falling, leveling off).
  • line graph — points connected by a line; best for change over time or a continuous variable.
  • bar graph — bars compare separate categories (four survey sites).
  • scatter plot — unconnected points showing how two measured variables relate.
  • dual-axis graph — a graph with a left y-axis and a right y-axis for two different data sets.
  • diagram / model — a drawing that represents a process or system (a food web, the water cycle).
  • translate — show the same information in another form (graph → sentence, table → graph).

All Science words in the glossary

1. Reading a short science text

GED science passages are short and packed with information. Read them like a scientist:

  1. Find the topic and purpose. Is the passage describing an experiment, explaining a process, or presenting data? The first and last sentences usually tell you.
  2. Underline what was measured and how. Look for words like measured, recorded, counted, compared.
  3. Notice definitions. Passages often define a term right in the text: "A resting heart rate is the number of times the heart beats in one minute while the animal is calm." The GED expects you to use that definition.
  4. Notice the rules of the model. "Each arrow points from an organism to the organism that eats it" is a rule you must apply.

Example: A passage says, "A stream biologist notes that the trout in one stream show signs of stress when dissolved oxygen falls below 9 mg/L." That one sentence gives you a cutoff number (9 mg/L), a direction (below), and what happens (stress). A question will probably ask you to combine that number with a graph.

2. Reading tables

A table is the most direct way scientists report data. Read it in this order:

  1. Title — what the whole table is about.
  2. Column headings and units — what each column measures. A heading like "Resting heart rate (beats per minute)" tells you both the quantity and the unit.
  3. Rows — usually one row per item, group or trial.
  4. Patterns — as one column goes up, what does another column do?

Example:

Elevation (feet)Boiling point of water (°F)
0 (sea level)212
2,000208
5,000203
10,000194
How to read a table, using the boiling-point table. Step 1: read the column headings and units, Elevation in feet and Boiling point of water in degrees Fahrenheit. Step 2: find the row you need, 5,000 feet, which is highlighted. Step 3: stay in that row and read across to the other column: 203 degrees Fahrenheit. Down the rows, as elevation increases, the boiling point decreases from 212 to 194. Reading a table: heading → row → across Elevation (feet) Boiling point (°F) 0 (sea level) 212 2,000 208 5,000 203 10,000 194 1. Read headings and units first 2. Find the row 3. Read across: 203 °F Pattern down the rows: higher elevation → lower boiling point
  • Find a value: At 5,000 feet, water boils at 203 °F.
  • See the pattern: As elevation increases, the boiling point decreases.
  • Watch units: 194 is in °F, not °C.

A common trap is reading the right row but the wrong column, especially when two columns contain similar-looking numbers (for example, in a table of mammals' mass and heart rate, a human's mass is 70 kg and a human's heart rate is 70 beats per minute).

3. Reading graphs (including two y-axes)

Every graph, every time, check these four things before reading any data:

  1. Title — what is being shown.
  2. Axes labels and units — what is on the x-axis and the y-axis.
  3. Scale — how much one gridline is worth. Gridlines might go up by 1, 2, 5, 10, 0.5 …
  4. Legend — which line, bar or symbol is which.
Line graph labeled with the four things to check before reading data. 1, Title: Oxygen water can hold vs. temperature. 2, Axis labels and units: x-axis Water temperature in degrees Celsius, y-axis Dissolved oxygen in milligrams per liter. 3, Scale: each gridline on the y-axis equals 2 milligrams per liter. 4, Legend: the blue line with dots is fresh water. Data points: 14.6 at 0 degrees, 11.3 at 10, 9.1 at 20, 7.6 at 30. The point at 20 degrees, 9.1 milligrams per liter, is traced to both axes. ① Title: Oxygen water can hold vs. temperature 0 2 4 6 8 10 12 14 16 0 10 20 30 ② Water temperature (°C) ② Dissolved oxygen (mg/L) data point: 20 °C, 9.1 mg/L fresh water ④ Legend ③ Scale: each gridline = 2 mg/L Check ① ② ③ ④ BEFORE reading any number.

Kinds of graphs:

Graph typeBest forHow to read it
Line graphchange over time or along a continuous variablefind x, go up to the line, go across to the y-axis
Bar graphcomparing separate groupscompare heights of bars against the y-axis
Scatter plotwhether two measured variables are relatedlook at the overall pattern of the cloud of points
Circle (pie) graphparts of a wholeeach slice is a percent of 100%

Reading between gridlines: If gridlines are 10 °F apart and a point sits halfway between 70 and 80, its value is 75 °F.

Reading between gridlines. A vertical axis has gridlines every 10 degrees Fahrenheit, labeled 60, 70, 80 and 90. A data point sits exactly halfway between the 70 and 80 gridlines, so its value is 75 degrees Fahrenheit. Reading between gridlines 60 °F 70 °F 80 °F 90 °F 10 °F halfway → 75 °F

Dual-axis graphs: Some graphs show two data sets with different units. A climate graph might show precipitation as bars (left axis, inches) and temperature as a line (right axis, °F). Match each series to its own axis. The legend or passage tells you which goes with which. Reading a bar against the right axis is one of the most common mistakes on the test.

Dual-axis climate graph for January to June. Precipitation is shown as bars read on the LEFT axis in inches, 0 to 5. Temperature is shown as a line read on the RIGHT axis in degrees Fahrenheit, 0 to 100. Values: January 3.0 inches and 30 degrees, February 2.5 and 35, March 3.5 and 45, April 4.0 and 55, May 4.5 and 65, June 3.8 and 75. April is traced: its bar reads 4.0 inches on the left axis, and its line point reads 55 degrees on the right axis. Two y-axes: match each series to its own axis 0 0 1 20 2 40 3 60 4 80 5 100 Jan Feb Mar Apr May Jun Precipitation (in.) — bars Temperature (°F) — line April bar → LEFT axis: 4.0 in. April point on line → RIGHT axis: 55 °F

Shape matters: A straight line rises or falls by the same amount each step. A curve that flattens out means the change is getting smaller. "Decreases quickly at first, then more slowly" describes a curve, not a straight line.

4. Diagrams and models

A model is a simplified picture of a real system. Diagrams on the GED include food webs and food chains, cycles (water, carbon, rock), body systems, flowcharts of a process, and labeled cross-sections (Earth's layers, a cell).

Key rule: find what the symbols mean. Arrows can mean different things in different diagrams:

  • In a food web, an arrow points from the food to the eater. It shows the direction energy flows. Grass → Rabbit means "the rabbit eats grass".
  • In a cycle, arrows show the order of steps: Ocean → (evaporation) → water vapor → (condensation) → clouds → (precipitation) → land → (runoff) → ocean.
  • In a flowchart, arrows show the sequence of a process.

Only use connections that are drawn. If a hawk sits at the top of a food web but there is no arrow from Frog to Hawk, then the hawk does not eat frogs directly in this model, even if you think hawks might eat frogs in real life. Answer from the model, not from outside opinions.

Food web model. Arrows point from the food to the eater, showing the direction energy flows. Grass to rabbit, grass to mouse, grass to insect, insect to frog, frog to snake, mouse to snake, rabbit to hawk, mouse to hawk, snake to hawk. There is no arrow from frog to hawk, so in this model the hawk does not eat frogs directly. Food web: each arrow points from the food TO the eater Grass Rabbit Mouse Insect Frog Snake Hawk red ✗: no Frog → Hawk arrow, so the hawk doesn't eat frogs here

5. Translating between forms

Many GED questions ask you to move information from one form to another:

  • Graph → words: "Which statement best describes the graph?"
  • Words → graph: "Which graph shows the results described?"
  • Graph → table: "Which table correctly lists the values?"
  • Diagram → sentence: "Complete the sentence based on the diagram."

Method:

  1. Pick out two or three checkable facts from the source (the highest point, the direction of the trend, one exact value).
  2. Test each answer choice against those facts.
  3. Eliminate any choice that gets one value wrong. One wrong value makes a choice wrong.
  4. For word summaries, check direction (up or down) and shape (steady, speeding up, leveling off), and make sure the sentence does not add information that the graph never showed.
Worked example

Worked example 1: Reading a table

Stimulus: the boiling-point table from Concept 2 (0 ft: 212 °F; 2,000 ft: 208 °F; 5,000 ft: 203 °F; 10,000 ft: 194 °F).

Question: According to the table, how much lower is the boiling point of water at 10,000 feet than at sea level? A. 18 °F B. 194 °F C. 9 °F D. 10,000 °F

Think-aloud:

  1. "Sea level" means 0 feet → 212 °F. At 10,000 feet → 194 °F.
  2. "How much lower" = subtract: 212 - 194 = 18 °F.
  3. B is just the value at 10,000 ft, not the difference. C is the drop from 5,000 to 10,000 ft (203 - 194 = 9), the wrong interval. D copies the elevation from the wrong column.

Answer: A, 18 °F.

Worked example

Worked example 2: Reading a bar graph

Bar graph titled Bird species counted at four sites. Site A 12 species, Site B 6, Site C 18, Site D 9. The y-axis shows number of species from 0 to 20. Site A Site B Site C Site D 0 4 8 12 16 20 Survey site Number of bird species

Stimulus: the bar graph below shows the number of bird species counted at four survey sites.

Question: Which site had about twice as many bird species as Site B? A. Site A B. Site C C. Site D D. None of the sites

Think-aloud:

  1. Check the axis: number of bird species, gridlines every 4.
  2. Site B's bar reaches 6, halfway between the 4 and 8 gridlines. Twice 6 is 12.
  3. Site A's bar reaches 12 → twice Site B. ✓
  4. Site C reaches 18, which is three times Site B. Site D reaches 9, which is one and a half times.

Answer: A, Site A.

Worked example

Worked example 3: Reading a diagram

Stimulus: "In the water cycle diagram, arrows show the order of the steps: Ocean → (evaporation) → water vapor → (condensation) → clouds → (precipitation) → land → (runoff) → ocean."

Question: According to the diagram, which process turns water vapor into clouds? A. evaporation B. condensation C. precipitation D. runoff

Think-aloud:

  1. Find "water vapor" and look at the arrow leaving it.
  2. The arrow from water vapor to clouds is labeled "condensation."
  3. Evaporation comes before water vapor (ocean → vapor). Precipitation comes after clouds. Runoff moves water from land to ocean.
Water cycle diagram as a loop of four stages. Ocean to water vapor, labeled evaporation. Water vapor to clouds, labeled condensation, highlighted. Clouds to land, labeled precipitation. Land back to ocean, labeled runoff. The arrow leaving water vapor is labeled condensation, so condensation turns water vapor into clouds. Water cycle: follow the arrow leaving "water vapor" Ocean Water vapor Clouds Land evaporation condensation precipitation runoff vapor → clouds = condensation (gas → liquid droplets)

Answer: B, condensation. The diagram's labels, not memory, give the answer.

Worked example

Worked example 4: Translating a table into words

Stimulus: A student recorded the temperature of a cup of hot coffee as it cooled.

Time (minutes)05101520
Temperature (°C)9070574842

Question: Which sentence best describes the data? A. The coffee cooled by the same amount every 5 minutes. B. The coffee cooled quickly at first and then more slowly. C. The coffee warmed up over time. D. The coffee will reach 0 °C after 40 minutes.

Think-aloud:

  1. Direction: temperatures go down → cooling (eliminate C).
  2. Size of each drop: 20, 13, 9, 6 °C. The drops shrink, so cooling slows (B fits; A does not).
  3. D goes beyond the data and ignores that coffee cools only to room temperature, about 20 °C, not to 0 °C.
Line graph of coffee temperature over time: 90 degrees Celsius at 0 minutes, 70 at 5, 57 at 10, 48 at 15, and 42 at 20 minutes. Each 5-minute drop is labeled: 20, then 13, then 9, then 6 degrees. The drops shrink, so the curve flattens: the coffee cooled quickly at first and then more slowly. Cooling coffee: the drops get smaller 30 40 50 60 70 80 90 100 0 5 10 15 20 Time (minutes) Temperature (°C) 90 70 57 48 42 drop 20 drop 13 drop 9 drop 6

Answer: B. A line graph of this data would be a curve that flattens out.

Common mistake

Common mistakes to avoid

  • Wrong row or column. Wrong: reading the human's mass (70) when asked for heart rate. Right: find the column heading first, then stay in one row.
  • Mixing up the axes on a dual-axis graph. Wrong: reading the top of a precipitation bar on the temperature axis. Right: bars with their axis, line with its axis, as the legend says.
  • Misjudging the scale. Wrong: assuming every gridline is 1 unit. Right: check the labeled ticks: if 0, 2, 4 are labeled, each gridline might be worth 1 or 2; count them.
  • Reversing arrows. Wrong: "Grass → Mouse" means grass eats the mouse. Right: in a food web, arrows point to the eater.
  • Adding outside information. Wrong: choosing "fish need more oxygen in cold water" when the graph only shows how much oxygen water can hold. Right: answer only from what the stimulus shows.
  • Ignoring the shape. Wrong: "decreases by the same amount each step" for a curve. Right: compare the size of each step.
Test strategy

GED test strategy

  • Read the question first, then the stimulus. Knowing what you need ("the wettest month") tells you where to look.
  • Do the four-point graph check every time: title, axis labels with units, scale, legend.
  • Put your finger (or the cursor) on the data. Trace from the x-value up to the point and across to the axis. You can also hold the edge of your erasable note board against the screen to keep your place.
  • Use the passage definitions. If the text defines a term or explains the symbols, that definition is the rule.
  • Eliminate on one wrong fact. A translation choice with even one wrong value is wrong.
  • Watch absolute and extra words. Choices with always, never, exactly, or claims about things never measured are usually traps.
  • Time: spend about 1 minute on each reading question.

Check yourself

Comprehending scientific presentations
Heart Rates of Mammals

Small animals and large animals live at very different speeds. A biology class compared the typical resting heart rates of six mammals. A resting heart rate is the number of times the heart beats in one minute while the animal is calm. The table shows approximate typical values for healthy adults.

AnimalTypical adult mass (kg)Resting heart rate (beats per minute)
Mouse0.02600
Cat4150
Medium dog20100
Human7070
Horse50040
Elephant5,00030

The class noted that, in general, larger mammals have slower resting heart rates than smaller mammals.

According to the table, which animal has a resting heart rate of 100 beats per minute?

Answer choices
Hint

Find 100 in the heart-rate column, then look left along the same row.

Check yourself

Comprehending scientific presentations
Heart Rates of Mammals

Small animals and large animals live at very different speeds. A biology class compared the typical resting heart rates of six mammals. A resting heart rate is the number of times the heart beats in one minute while the animal is calm. The table shows approximate typical values for healthy adults.

AnimalTypical adult mass (kg)Resting heart rate (beats per minute)
Mouse0.02600
Cat4150
Medium dog20100
Human7070
Horse50040
Elephant5,00030

The class noted that, in general, larger mammals have slower resting heart rates than smaller mammals.

Which statement best describes the relationship shown in the table?

Answer choices
Hint

Look at how the numbers in the mass column change as you go down. Then see what happens to the heart rates in the same rows.

Summary

  • Read every science stimulus for its topic, what was measured, units, and any definitions or rules.
  • In tables, find the right column heading first, then stay in one row.
  • In graphs, check title, axes, units, scale and legend before reading values; on dual-axis graphs match each series to its own axis.
  • In diagrams, find what the arrows and symbols mean, and use only connections that are drawn.
  • To translate between forms, test each choice against two or three exact facts and reject any choice with a single wrong fact.
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