Scientific Inquiry, Processes, and the Nature of Science
Domain 1: Scientific Inquiry, Processes, and the Nature of Science
This domain tests how well you can design investigations, interpret data, and explain how scientific knowledge is built and revised. Expect questions on variables, controls, measurement, graphing, error, and the distinction between hypotheses, theories, and laws.
Experimental design
A testable question names a cause-and-effect relationship. The independent variable is what the investigator changes; the dependent variable is the measured response; constants are held fixed; a control group receives no treatment or a standard treatment. Repeated trials reduce random error. A large sample reduces the influence of individual variation.
Measurement, data, and error
Use SI units: meter, kilogram, second, ampere, kelvin, mole, candela. Precision is repeatability; accuracy is closeness to the true value. Systematic error shifts all results in one direction; random error scatters results. Graphs should match the data type: line graphs for continuous change, bar graphs for categories, scatterplots for association. Significant figures reflect measurement uncertainty; do not report more digits than the instrument supports.
Nature of science
Scientific knowledge is empirical, tentative, and self-correcting. A hypothesis is a testable prediction; a theory is a well-supported explanation of a broad body of evidence; a law describes a consistent relationship, often mathematically. Theories do not "become" laws. Peer review, replication, and open data strengthen claims. Correlation alone does not establish causation.
Worked example
A student predicts that fertilizer increases bean plant height. She plants 20 identical bean seedlings in identical pots with the same soil, water, light, and temperature. Ten plants receive 5 mL of fertilizer solution weekly; ten receive 5 mL of plain water. After four weeks she measures height. Reasoning: The independent variable is fertilizer treatment; the dependent variable is plant height; constants include pot size, soil, water volume, light, and temperature. The plain-water group is the control. Twenty plants reduce chance variation. To strengthen the conclusion, she should randomize pot positions and repeat the experiment. If fertilized plants are taller on average, the prediction is supported, not proved.
Traps that cost marks
Do not call the control group a "constant"; constants are conditions held the same for all groups. Do not say a theory is "just a guess". Do not confuse precision with accuracy. Do not treat a single trial as conclusive. Do not claim causation from an observed correlation.