Making Sense of Data
The optional ACT Science test is really a reading test about data. Data representation passages give you graphs, tables, and diagrams and ask you to read them accurately. You rarely need outside science facts.
Read the Labels First
Before looking at any data point, read the title, the axis labels, and the units. Knowing that the x-axis is "time (seconds)" and the y-axis is "temperature (degrees C)" prevents most errors. Note the scale: do gridlines count by 2, 5, or 10?
Find Specific Values
Many questions simply ask you to read a point. Trace from the axis to the curve and back to the other axis. Estimate carefully if a value falls between gridlines.
Identify Trends
Look at the overall shape:
- •Direct relationship: as x increases, y increases.
- •Inverse relationship: as x increases, y decreases.
- •No relationship: y stays roughly constant. Describe the trend in plain words, then match it to the answer.
Interpolate and Extrapolate
- •Interpolate: estimate a value between known data points.
- •Extrapolate: extend a trend beyond the data to predict a value. Assume the pattern continues unless told otherwise.
Compare Multiple Lines
When a graph shows several curves, use the legend to tell them apart. Questions often ask which variable is highest at a given point or where two curves cross.
Key Takeaways
- •Always read titles, axes, and units before the data.
- •Trace carefully to read individual values.
- •Classify trends as direct, inverse, or none.
- •Interpolate between points and extrapolate beyond them by continuing the pattern.
