Scientific Inquiry and the Nature of Science
What to know
Scientific inquiry covers the logic of hypothesis testing, experimental design, and the social process of science. Candidates should be able to distinguish a hypothesis (a testable, falsifiable prediction) from a theory (a broad, well-supported explanatory framework) and from a law (a descriptive regularity). Understand independent and dependent variables, control and experimental groups, constants, and the role of replication and peer review. Know the difference between correlation and causation, and between a sample and a population. Recognize sources of error (random vs. systematic) and the meaning of precision versus accuracy.
Traps
Questions often present a scenario and ask which variable is controlled or which conclusion is justified. A common trap is choosing a conclusion that goes beyond the data (overgeneralization) or that confuses a hypothesis with a theory. Another trap: a well-designed experiment must change only one variable at a time; if two change, the cause cannot be isolated. Watch for questions about sample size and bias, and for the claim that a single study proves a theory.
Worked example
A student waters plants with 0, 50, or 100 mL of fertilizer solution and measures height after two weeks. The fertilizer amount is the independent variable; plant height is the dependent variable; light, soil, and water must be held constant. If height increases with fertilizer, the data support a hypothesis but do not prove causation beyond the tested range. Rule of thumb: an experiment can only support or fail to support a hypothesis, never prove it absolutely.
Rule of thumb
If a question asks what a study shows, pick the answer that stays within the tested variables and conditions.