Science: Variables, Data, and Defensible Conclusions
Science is a reasoning test, not a memory test
ACT Aspire Science presents experiments, tables, graphs, and conflicting viewpoints, then asks you to interpret them. You need to identify the independent variable (what the researcher changed), the dependent variable (what was measured), constants, and controls. You should read axes and units carefully, describe trends, interpolate within the data, and recognize when a claim goes beyond the evidence. Comparison questions ask how two experiments differ; evaluation questions ask which hypothesis is supported.
Traps include treating correlation as causation, ignoring a change in scale, and choosing an answer that is true scientifically but not shown by the data. A control group is not the same as a constant. If a graph's line rises and then falls, the relationship is not simply 'positive.' Extrapolating far beyond the tested range is risky. Also watch for questions that ask what would happen 'if' a variable changed, which require applying the observed relationship rather than recalling a fact.
Worked example: A table shows a plant's growth increasing as light increases from 2 to 6 hours, then decreasing at 8 hours. A question asks for the best conclusion. 'More light always increases growth' is wrong because growth falls at 8 hours. The defensible conclusion is that growth increases up to about 6 hours and then declines. Rule of thumb: state the relationship in words - 'as X increases, Y does this' - and check that your sentence is true at every data point shown.