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Expressing Scientific Information

Choose the best graph, table or model, describe data accurately in words, and use scientific vocabulary precisely.

Practice this skill 18 min Expressing scientific information Leer en español
Key idea

What you'll learn

Scientists do not just collect data — they have to communicate it. A good table, graph or diagram can make a pattern obvious at a glance; a poor one can hide it or even mislead. The GED calls this skill expressing scientific information.

In this lesson you will learn to:

  • choose the best display (table, line graph, bar graph, circle graph, scatter plot, diagram or model) for a set of data;
  • set up a graph correctly: title, axes, labels, units and scale;
  • describe data in words accurately — trends, highest and lowest values, comparisons and rates;
  • use scientific vocabulary precisely, including words for relationships (direct, inverse), variables and processes shown in models.

How it shows up on the GED: You might see a table and be asked which of four graphs represents it best, or a graph and be asked which sentence describes it correctly. Drag-and-drop items may ask you to match data sets to displays or to place labels on a diagram. Drop-down items may ask you to complete a summary sentence with the right number or word. Hot-spot items may ask you to click the part of a model that shows a named process.

Words to know

Key terms

  • data — measurements or observations collected in a study (12 monthly temperatures).
  • table — data organized in rows and columns; best when exact values matter.
  • line graph — points joined by a line; best for change over time or change along a continuous scale (temperature by month).
  • bar graph — bars of different heights; best for comparing separate categories (species in four habitats).
  • circle (pie) graph — slices of a circle; best for parts of a whole that add up to 100% (gases in air).
  • scatter plot — unconnected points, each showing two measurements for one individual; best for the relationship between two variables (height vs. arm span).
  • model — a simplified representation of a real system, such as a diagram, a physical model or an equation (a water-cycle diagram).
  • axis — a reference line on a graph. The x-axis is horizontal; the y-axis is vertical.
  • independent variable — the variable that is chosen or changed; it goes on the x-axis (time, temperature set by the scientist).
  • dependent variable — the variable that is measured; it goes on the y-axis (growth, dissolved oxygen).
  • trend — the general direction of data: increasing, decreasing, peaking, leveling off.
  • direct (positive) relationship — both variables increase together.
  • inverse (negative) relationship — one variable increases as the other decreases.

All Science words in the glossary

1. Choosing the best display

Every kind of display has a job. Choose the one whose job matches the question the data answer.

DisplayIts jobExample
TableShow exact values; organize raw dataFreezing points at four salt amounts
Line graphShow change over time or along a continuous scaleCO₂ each year, 2015–2023
Bar graphCompare separate categoriesSpecies in forest, wetland, grassland, park
Circle graphShow parts of a whole (adds to 100%)Nitrogen 78%, oxygen 21%, other 1%
Scatter plotShow whether two measured variables are relatedHeight vs. arm span for 30 people
Diagram or modelShow structure, steps or processesWater cycle, food web, cell parts
Punnett squarePredict offspring of a genetic crossTt × Tt
Four kinds of display and their jobs. A line graph shows change over time. A bar graph compares separate categories, such as four habitats. A circle graph shows parts of a whole, such as air: nitrogen 78 percent, oxygen 21 percent, other 1 percent. A scatter plot shows the relationship between two variables, such as height and arm span. Line graphchange over timetime →Bar graphcompare categories4 habitatsCircle graphparts of a wholeN₂ 78%O₂21%Scatter plotrelationshipheight vs. arm span

Quick questions to ask:

  • Is there time or another continuous scale (temperature, distance, dose)? → line graph.
  • Are the groups separate names with no in-between values? → bar graph.
  • Do the numbers add up to a total, usually 100%? → circle graph.
  • Are there two measurements for each individual, and you want to see whether they are related? → scatter plot.
  • Do you need a process or structure, not numbers? → diagram or model.

2. Building a graph correctly

A well-made graph follows conventions so anyone can read it.

  1. Title — says exactly what is shown: the variable, the subject or place, and often the time span. "Average Monthly Temperature in Lakeview (°F)" is good. A title should not make claims the data do not show, like "Temperature Causes the Seasons."
  2. Independent variable on the x-axis (horizontal). This is what was chosen or changed — time, temperature setting, amount of fertilizer.
  3. Dependent variable on the y-axis (vertical). This is what was measured — growth, rate, oxygen.
  4. Axis labels with units — "Temperature (°C)," "Yield (bushels per acre)." Without units, numbers are meaningless.
  5. An even scale — equal spaces stand for equal amounts (0, 5, 10, 15…). Uneven scales distort trends.
  6. A legend if there is more than one data series.

Example. A student tests how the amount of fertilizer (0, 5, 10, 15 g) affects plant height. Fertilizer is independent → x-axis, labeled "Fertilizer (g)." Height is dependent → y-axis, labeled "Plant height (cm)."

Blank graph set up for the fertilizer experiment, with callouts. Title: Effect of Fertilizer on Plant Height. The x-axis shows the independent variable, Fertilizer in grams, with an even scale of 0, 5, 10, 15. The y-axis shows the dependent variable, Plant height in centimeters. Both axis labels include units. Effect of Fertilizer on Plant Height010203040051015Fertilizer (g)Plant height (cm)① Title: what is shown② y-axis = dependent(what is measured)③ x-axis = independent(what is chosen)④ Labels include units (g, cm) ⑤ Even scale: 0, 5, 10, 15

Watch for misleading graphs. A y-axis that starts at 95 instead of 0 can make a small difference look huge. The GED may ask why a graph is misleading or which graph shows the data most accurately. Always read the numbers on the axis, not just the heights of the bars.

The same two values, 97 and 99, drawn as bar graphs twice. On the left the y-axis starts at 95, so Group B’s bar looks three times as tall as Group A’s: misleading. On the right the y-axis starts at 0, so the bars look almost equal: accurate. y-axis starts at 95: misleading97999596979899100ScoreGroup AGroup By-axis starts at 0: accurate9799020406080100ScoreGroup AGroup BSame data (97 and 99). On the left, B looks twice as tall as A.

3. Describing data in words

Turning a graph or table into an accurate sentence is a core GED skill. A strong description has three parts:

  1. The trend — rises, falls, rises then falls, peaks, levels off, stays about the same.
  2. Key values with units — the highest and lowest values and where they occur ("a high of 75 °F in July").
  3. Size or rate of change when useful — "about 2.6 ppm per year."

Useful trend words:

PatternWords to use
Goes upincreases, rises, grows
Goes downdecreases, falls, declines, drops
Up then downpeaks at, reaches a maximum at
Changes less and lesslevels off, slows, flattens
Same change each stepsteady, constant rate, linear

Comparing values. "Times as many" means divide: 41 species ÷ 12 species ≈ 3.4, so more than three times as many. "Difference" or "how many more" means subtract: 41 - 12 = 29.

Rate of change = change in the measured value ÷ change in time. CO₂ rose from 400 to 421 ppm from 2015 to 2023: \dfrac{421 - 400}{2023 - 2015} = \dfrac{21}{8} \approx 2.6 ppm per year. Count intervals (8), not data points (9).

Graph of carbon dioxide from 2015 to 2023. It rose from 400 parts per million in 2015 to 421 in 2023. The change in time is 8 years, which is 8 intervals between 9 yearly points; the change in CO2 is 21 ppm. Rate equals 21 divided by 8, about 2.6 ppm per year. 390395400405410415420425201520162017201820192020202120222023YearCO₂ (ppm)400 ppm421 ppmchange in time: 2023 − 2015 = 8 years (8 intervals)change: 21 ppmrate = 21 ÷ 8 ≈ 2.6 ppm per year

Accurate means not over-claiming. "Oxygen decreases as temperature rises" is accurate. "Fish die at 30 °C" is not, if the data are only about oxygen. A description should never add a cause, a prediction far outside the data, or the word "always" unless the data truly justify it.

4. Scientific vocabulary and models

On the GED, many answer choices differ by just one scientific word. Precise vocabulary is how scientists avoid confusion.

Words for relationships and evidence:

  • Direct vs. inverse. Height and arm span increase together (direct). Temperature up, dissolved oxygen down (inverse).
  • Correlation vs. causation. A correlation means two variables change together; it does not prove that one causes the other.
  • Hypothesis vs. theory. A hypothesis is a testable idea for one investigation. A scientific theory is a well-tested explanation supported by many lines of evidence (the theory of evolution, the cell theory). "Just a theory" is not how scientists use the word.

Reading models. A model leaves out details to show what matters. In a diagram, read each arrow as "from → to":

  • From ocean surface up into air: evaporation.
  • From plant leaves up: transpiration.
  • Vapor into a cloud as droplets: condensation.
  • From cloud down to ground: precipitation.
  • Along the ground into rivers or ocean: runoff.
Water-cycle model read as from-to arrows. Evaporation: from the ocean surface up into the air. Transpiration: from plant leaves up. Condensation: vapor into a cloud as droplets. Precipitation: from the cloud down to the ground. Runoff: along the ground into the ocean. oceanrunoff (into ocean)plantcloudevaporationtranspirationcondensation(vapor → cloud)precipitationRead each arrow“from → to”

The same "from → to" reading works for food webs (arrows point from the food to the eater, showing energy flow), the carbon cycle and the rock cycle.

Worked example

Worked example 1: Picking the right graph

Stimulus. A nurse records a patient's body temperature every 2 hours for 12 hours: 98.6, 99.1, 100.4, 101.2, 100.8, 99.5, 98.9 °F.

Question. Which display best shows how the patient's temperature changed over those 12 hours?

A. Circle graph B. Bar graph of the seven readings in order from smallest to largest C. Line graph with time on the x-axis D. Scatter plot of temperature vs. patient's age

Think-aloud.

  1. The data are one measurement repeated over time. Job: change over time → line graph.
  2. Time is the independent variable (chosen by the nurse), so it goes on the x-axis. C does that. ✓
  3. A — the readings are not parts of a whole. ✗ B — sorting by size destroys the time order, so you cannot see the fever rise and fall. ✗ D — there is only one patient, so age does not vary. ✗
Line graph of a patient’s body temperature every 2 hours: 98.6, 99.1, 100.4, 101.2, 100.8, 99.5 and 98.9 degrees Fahrenheit at 0, 2, 4, 6, 8, 10 and 12 hours. Time is on the x-axis, so the fever’s rise and fall is easy to see. 9899100101102024681012Time (hours after first reading)Body temperature (°F)98.699.1100.4101.2100.899.598.9

Answer: C.

Worked example

Worked example 2: Describing a graph in words

Stimulus. A graph shows the population of deer in a park: 2018: 120; 2019: 160; 2020: 210; 2021: 230; 2022: 235; 2023: 236.

Question. Which sentence best describes the data?

A. The deer population grew at a constant rate. B. The deer population grew quickly at first, then leveled off at about 235. C. The deer population will reach 300 by 2026. D. The deer population fell after 2021.

Think-aloud.

  1. Find the year-to-year changes: +40, +50, +20, +5, +1. Large at first, then tiny.
  2. "Grew quickly, then leveled off" matches. B ✓
  3. A — the changes are not equal. ✗ C — a prediction far beyond the data, and the trend is flattening. ✗ D — the numbers keep rising slightly; they never fall. ✗
Line graph of deer in a park: 120 in 2018, 160 in 2019, 210 in 2020, 230 in 2021, 235 in 2022 and 236 in 2023. The yearly increases are plus 40, plus 50, plus 20, plus 5 and plus 1: quick growth at first, then leveling off. 050100150200250201820192020202120222023YearNumber of deer+40+50+20+5+1120160210230235236

Answer: B.

Worked example

Worked example 3: Finding the best graph of a table

Stimulus.

Mass on spring (g)0100200300
Spring length (cm)10141822

Question. A student graphs these data. Which description of a correct graph is right?

A. x-axis "Spring length (cm)," y-axis "Mass (g)," line rising. B. x-axis "Mass (g)," y-axis "Spring length (cm)," straight line rising from 10 to 22. C. x-axis "Mass (g)," y-axis "Spring length (cm)," line starting at 0 cm. D. Circle graph with four slices.

Think-aloud.

  1. The student chose the masses → independent → x-axis. Length was measured → dependent → y-axis. That rules out A.
  2. Check values: at 0 g the length is 10 cm, not 0. C starts at 0, so it misplots. ✗
  3. Each 100 g adds 4 cm — a steady change, so a straight rising line. B ✓
  4. D — not parts of a whole. ✗
Correct graph of the spring data: mass in grams on the x-axis, spring length in centimeters on the y-axis. Points at 0 grams, 10 centimeters; 100 grams, 14; 200 grams, 18; 300 grams, 22. Each 100 grams adds 4 centimeters, so the line is straight and starts at 10 centimeters, not 0. 05101520250100200300Mass on spring (g)Spring length (cm)+4+4+410 cm at 0 g (not 0)14 cm18 cm22 cm

Answer: B.

Worked example

Worked example 4: Choosing the precise word

Stimulus. A study finds that cities with more ice cream sales also have more drownings in summer months.

Question. Which statement uses scientific vocabulary correctly?

A. Ice cream sales cause drownings. B. Ice cream sales and drownings are correlated, but the data do not show that one causes the other. C. Ice cream sales and drownings have an inverse relationship. D. The study proves the theory that ice cream is dangerous.

Think-aloud.

  1. Both numbers go up together → a direct relationship, and a correlation. C says inverse. ✗
  2. Do the data show cause? No — a third factor (hot weather) likely raises both. A claims cause. ✗
  3. D misuses "proves" and "theory." ✗
  4. B states the correlation and correctly limits the claim. ✓
Diagram of a third factor. Hot weather raises ice cream sales and also raises swimming, which raises drownings. Ice cream sales and drownings are linked by a dashed two-way arrow labeled: correlated, rising together, but neither causes the other. Hot weatherMore ice cream salesMore swimming →more drowningsraisesraisescorrelated (rise together)but neither causes the other

Answer: B.

Common mistake

Common mistakes

  • Using a circle graph for data that are not parts of a whole. Wrong: a pie chart of temperatures at four times. Right: circle graphs only for parts that add up to a total (usually 100%).
  • Swapping the axes. Wrong: time on the y-axis. Right: the independent variable (what is chosen or changed, often time) goes on the x-axis; the measured variable goes on the y-axis.
  • Describing only part of a trend. Wrong: "Temperature rises all year" when it rises then falls. Right: describe the whole pattern, including the peak and what happens after.
  • Mixing up "times as many" and "difference." Wrong: "41 is 29 times as many as 12." Right: 41 \div 12 \approx 3.4 times; the difference is 41 - 12 = 29.
  • Confusing direct and inverse. Wrong: "Oxygen and temperature are directly related" when one falls as the other rises. Right: opposite directions = inverse (negative).
  • Reading a model's arrows backward. Wrong: "Arrow from grass to rabbit means grass eats rabbit." Right: arrows show the flow of matter or energy, from → to.
Test strategy

GED strategy for expressing scientific information

  1. Name the job first. Before looking at answer choices, decide: change over time, compare categories, parts of a whole, or relationship? Then find the display that does that job.
  2. Check axes and units on every graph choice. Many wrong graphs have swapped axes, missing units, or a scale that does not start where it should.
  3. Test two data points. To choose the graph that matches a table, check two rows — for example, the first and last values. A graph with the wrong direction or wrong values fails immediately.
  4. Calculate before you judge words. For "steady," "twice," "the same amount" or "faster," compute the actual changes or ratios.
  5. Prefer the precise, modest statement. Accurate descriptions stay within the data. Reject choices with "proves," "always," invented causes or predictions far outside the range.
  6. For models, trace the arrows. Say each one aloud as "from ___ to ___" and match it to the definition.

Check yourself

Expressing scientific information
A Year of Temperatures

A student volunteer at a weather station collected the average temperature for each month in the city of Lakeview, a northern U.S. city near a large lake. Each value is the average of the daily temperatures recorded during that month, combined over many years so that one unusually warm or cold year does not distort the results. She wants to share the data on a science fair poster so that visitors can quickly see how temperature changes through the seasons.

MonthAverage temperature (°F)
January24
February28
March38
April49
May60
June70
July75
August73
September66
October53
November40
December29

The student wants a display that shows clearly how Lakeview's average temperature changes over the year. Which display is best?

Answer choices
Hint

Which kind of graph is designed to show change over time? Also think about which variable goes on which axis.

Check yourself

Expressing scientific information
A Year of Temperatures

A student volunteer at a weather station collected the average temperature for each month in the city of Lakeview, a northern U.S. city near a large lake. Each value is the average of the daily temperatures recorded during that month, combined over many years so that one unusually warm or cold year does not distort the results. She wants to share the data on a science fair poster so that visitors can quickly see how temperature changes through the seasons.

MonthAverage temperature (°F)
January24
February28
March38
April49
May60
June70
July75
August73
September66
October53
November40
December29

Which sentence best describes the data in words?

Answer choices
Hint

Find the lowest and highest values and the months they occur. Then check whether the change is steady.

Summary

  • Match the display to its job: line = change over time, bar = compare categories, circle = parts of a whole, scatter = relationship between two variables, diagram/model = processes and structures.
  • Put the independent variable on the x-axis and the dependent variable on the y-axis; include a clear title, labels and units, and an even scale.
  • Describe data with the trend, key values with units, and the size or rate of change — without over-claiming.
  • "Times as many" = divide; "difference" = subtract; rate = change in value ÷ change in time.
  • Use vocabulary precisely: direct vs. inverse, correlation vs. causation, hypothesis vs. theory.
  • Read model arrows as "from → to."
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