Scientific Inquiry and Process Skills
What you must understand
Scientific inquiry is a repeatable system for turning curiosity into reliable evidence. Know the difference between an observation (what you detect with senses or instruments) and an inference (a conclusion drawn from observations). Understand the parts of a controlled experiment: the independent variable (what the investigator deliberately changes), the dependent variable (what is measured as a result), and controlled variables (everything else held constant). Recognize the purpose of a control group and of repeated trials to reduce random error. Distinguish accuracy (closeness to the true value) from precision (closeness of repeated measurements to each other). Know that a hypothesis is a testable prediction, not a guess, and that a theory is a well-supported explanation built from many lines of evidence - not an unproven idea.
Traps to expect
Questions often swap independent and dependent variables, or label a value held constant as the independent variable. Watch for "the conclusion proves" - experiments support or fail to support hypotheses; they rarely prove them outright. Another common trap is confusing a larger sample size with a fairer design when the procedure itself is biased. Also be careful with graphs: a line graph suits continuous data, a bar graph suits categories, and the axis labels must match the variables.
Worked example / rule of thumb
A student tests whether fertilizer affects plant height. Fertilizer amount is the independent variable; plant height is the dependent variable; light, water, soil, and pot size are controlled. The rule of thumb: "I change it, I measure it, I keep everything else the same." If a question asks what is wrong with a design, look first for a variable that was not controlled or a missing comparison group.
Key ideas
- Observation vs. inference
- Independent, dependent, and controlled variables
- Control groups and repeated trials
- Accuracy vs. precision
- Testable hypotheses and evidence-based conclusions