Scientific Inquiry, Practices, and Crosscutting Concepts
Core concepts to master
This domain tests how science works as a process. You should be able to identify a hypothesis, distinguish independent and dependent variables, and recognize controlled variables and control groups. Understand the difference between observation and inference, and between correlation and causation. Know how to design a fair test, evaluate the reliability of data, and interpret simple tables and graphs. Recognize the roles of models, theories, and laws, and how evidence leads to revised explanations. You should also understand crosscutting concepts such as cause and effect, patterns, scale and proportion, systems and system models, energy and matter flows, stability and change, and structure and function. Be able to describe the steps of the scientific method flexibly, since real investigations often revisit and refine questions.
Traps to watch for
A hypothesis is a testable prediction, not a guess or a proven fact. The independent variable is what the experimenter changes; the dependent variable is what is measured. A control group receives no treatment or a standard treatment, allowing comparison. Correlation does not prove causation, and a single trial rarely establishes reliability. Theories do not become laws; they serve different purposes, with theories explaining and laws describing. Be wary of questions that confuse sample size with accuracy.
Worked example and rule of thumb
A student tests whether fertilizer affects plant growth by giving one group fertilizer and another group water only, keeping light and soil the same. Fertilizer is the independent variable, plant height is the dependent variable, and light and soil are controlled variables. Rule of thumb: change one thing, measure one thing, and keep everything else the same; then use repeated trials and evidence to judge whether the result is reliable.