Science: Reading Scientific Data

This is Unit Nineteen of ACT Preparation, and the start of the science section: reading scientific data. The reading section closed by relating a chart to a passage; science builds on that skill. One habit governs it: read the units and the scale before any number, and describe what the whole series does. Science questions test reading, not recall. By the end you will be able to read a value from a table. To read every kind of graph. To describe a trend, including its peak. To interpolate and extrapolate. And to compute from data and combine two figures.

Three entries on the science formats and on tables.

Three formats.

ACT 1801 The Three Science Formats

The science section uses three formats: data representation, built on tables and graphs; research summaries, describing experiments; and conflicting viewpoints. Calculators are not allowed. Some questions need introductory background knowledge; the passage decides the rest.

Reading a table.

ACT 1802 Reading a Table

A science table lists values in rows and columns; read the title, headings and units before the numbers. Each cell pairs a condition with a result: in an invented table, the row for thirty degrees and the column for seeds sprouted meet at forty-two. Units sit in the headings.

Finding a value, step by step.

ACT 1803 Finding a Value in a Table

Identify the condition and the measured quantity, find their row and column, and read the cell, reading a second cell for a comparison. In an invented table of fifty seeds, forty-two sprouted at thirty degrees and twenty-eight at twenty, fourteen more; fifteen at forty degrees is thirty percent. The cells count seeds, so forty-two is a count, not a percent.

Five entries on graphs.

Line graphs.

ACT 1804 Reading a Line Graph

A line graph shows how a measured quantity changes with another, usually with the quantity the scientist set across the bottom. An invented graph of water heated from twenty degrees to eighty over six minutes rises. Read both axis labels and units first.

Bar graphs.

ACT 1805 Bar Graphs in Science

A bar graph compares a measured quantity across separate categories, such as species, sites or treatments: invented earthworm counts of twelve, thirty and seven for three soils. Bars compare categories; a line would suggest a smooth change never measured.

Several series on one graph.

ACT 1806 Graphs With More Than One Series

A graph can show several data series, each marked by its own line style or symbol and explained in a legend: invented plant heights in full sun and in shade. Match each line to the legend first; swapping the series reverses the conclusion.

Reading a value, step by step.

ACT 1807 Reading a Value From a Graph

Find the input on the horizontal axis, go straight up to the right line, then straight across, estimating between gridlines. On an invented graph of a cart's speed, marked every twenty, three seconds meets the line halfway between forty and sixty, so about fifty centimeters per second. Check the scale's step before estimating.

Scatter plots.

ACT 1808 Scatter Plots of Measurements

A scatter plot shows paired measurements as points, one per observation, and the overall pattern shows how they relate: invented leaf lengths and widths form a rising band. Describe the whole cloud, not one point.

Four entries on trends.

The direction of data.

ACT 1809 Trends

A trend is the overall direction of data: increasing, decreasing, steady, or changing direction. Invented readings of four, seven, nine, ten, ten increase, then level off. Name the trend from the whole series, and describe each part if it changes.

Direct and inverse.

ACT 1810 Direct and Inverse Relationships

In a direct relationship two quantities increase together; in an inverse one, one increases as the other decreases. A spring stretching more under more mass is direct; filling time falling as pump rate rises is inverse. Unit eleven's direct variation is the strict case; data can rise together without being proportional.

Highest and lowest.

ACT 1811 Maximum and Minimum

The maximum is the highest value and the minimum the lowest, and a question may ask at what condition the maximum occurs. Invented enzyme activity peaks at thirty-seven degrees, at ninety-two units. Give the half asked for: the condition or the value.

Describing a trend, step by step.

ACT 1812 Describing a Trend

Read the values in order of the horizontal quantity, note each change and any turn, and choose the answer that describes the whole series. An invented reaction rate of three, eight, fifteen, eleven and four across ten to fifty degrees rises to a maximum near thirty, then decreases; "the rate increases with temperature" describes only the first half. Check the last values before accepting "increases."

Four entries on estimating between and beyond the data.

Estimating between points.

ACT 1813 Interpolation in Data

Interpolating means estimating a value between two measured points, assuming the trend continues smoothly between them. An invented plant at ten centimeters on day four and sixteen on day six was likely about thirteen on day five. It is safest when the points are close together.

Estimating beyond the data.

ACT 1814 Extrapolation in Data

Extrapolating means extending a trend beyond the measured range, and it is less certain, because the trend may change. An invented plant growing three centimeters a day reached eighteen on day six, suggesting about twenty-four on day eight. An extrapolated answer carries a condition: if the trend continues.

Interpolating, step by step.

ACT 1815 Interpolating a Value

Find the measured points on either side, find what fraction of the way the condition sits, and move that fraction between the values. An invented sensor reads 331 at zero degrees and 343 at twenty; five degrees is a quarter of the way, so a quarter of twelve, three, gives 334. An interpolated value must lie between its neighbors.

Extrapolating, step by step.

ACT 1816 Extrapolating a Trend

Find the pattern in the last few points, a steady difference, a steady ratio, or a leveling off, and continue it. An invented culture of five, ten, twenty, forty thousand doubles each hour, so at hour five it would be 160 thousand, if doubling continues. Eighty mistakes the doubling for a steady difference. Decide whether the pattern adds or multiplies.

Eight entries on scale, quick arithmetic, and combining tables and figures, ending with one full passage.

Units and scale.

ACT 1817 Units and Scale

Every axis and column has units and a scale: check whether it starts at zero, what each gridline is worth, and whether two figures use different units. Five hundred grams on one invented graph is 0.5 kilograms on another. A scale starting at ninety makes small differences look large.

Estimating without a calculator.

ACT 1818 Estimating Without a Calculator

Science questions need only simple arithmetic, and rounding to friendly numbers is often enough: forty-seven out of 198 is close to fifty out of 200, about twenty-five percent. Estimate only as finely as the choices require.

Arithmetic from data, step by step.

ACT 1819 Quick Arithmetic From Data

Read the values with units, choose the operation, a difference, a ratio or a percent change, then round and compute. An invented pond had 240 frogs in 2010 and 180 in 2020: sixty fewer, a twenty-five percent fall, and the earlier count about 1.3 times larger. Percent change divides by the starting value; sixty over 180 uses the wrong base.

A table as a graph.

ACT 1820 Translating a Table Into a Graph

A table becomes a graph by putting each row's condition on the horizontal axis and its measured value on the vertical, one point per row. Invented times of zero, ten and twenty minutes with temperatures of five, fifteen and twenty-five make three points on a rising line.

Matching a table to a graph, step by step.

ACT 1821 Matching a Table to a Graph

Check the axes and units, describe the table's trend, and test two specific points against each graph. An invented sensor reading 1.0 at twenty-five seconds, 1.4 at fifty and 2.0 at one hundred rises more slowly over time, so the matching graph rises steeply, then flattens, through those points. Many graphs share the right direction; specific points pick the right one.

Two figures, one shared quantity.

ACT 1822 Two Figures, One Variable

Some passages give two figures that share a quantity, so a value read from the first can be carried into the second. An invented lake's temperature by month and oxygen by temperature together give oxygen by month. Confirm the shared quantity has the same units in both.

Combining two figures, step by step.

ACT 1823 Combining Two Figures

Find the shared quantity, read the first figure at the given condition, and carry that value into the second. An invented pond reaches twenty-four degrees in July, and the second figure gives eight milligrams per liter of oxygen at twenty-four degrees, so July's oxygen is about eight. Carry the exact value when the second curve is steep.

The whole unit in one passage.

ACT 1824 A Data Representation Passage

Data representation tests reading, not recall. In an invented passage, radish seedlings under lamps of 100 to 400 units grow two, five, seven and 7.5 centimeters, and a second table gives leaves by height. The trend rises quickly, then levels off between 300 and 400. At 250 units, height is about six centimeters, halfway between five and seven. From 100 to 200 units, height rose 150 percent. At 300 units, seven centimeters gives six leaves from the second table. And at 500 units, the leveling suggests about 7.5 centimeters, not the fourteen a straight line through the first two points would give. Read units first, describe the whole series, and state every extrapolation with its condition.

Look at what you can now do. You can read a table where a condition meets a measurement, noticing what each number counts. You can read any graph, checking the legend and the scale's step. You can describe a trend across the whole series, including where it peaks or levels. You can interpolate between points and extrapolate beyond them, with the condition stated. And you can compute with friendly numbers and carry a value from one figure to another. Unit twenty turns from reading data to judging how it was produced: experiments.