Chapter 1. The Nature of Science and the Scientific Method

Science is a way of learning about the natural world through observation, evidence and testable explanations [1][2].

Key terms

Observation: information gathered with the senses or instruments.

Hypothesis: a testable, tentative explanation.

Theory: a well-tested explanation supported by a large body of evidence. In science, a theory is not a “mere guess.”

Law: a concise description of a regularity in nature, often as a mathematical relationship.

Model: a representation used to explain or predict.

The scientific method (a flexible cycle, not a fixed recipe)

Ask a question based on observation.

Research what is already known.

Form a hypothesis.

Design and run a controlled experiment.

Collect and analyze data.

Draw conclusions and share results.

Repeat, since new evidence may refine or replace earlier ideas.

Experimental design. The independent variable is changed by the experimenter; the dependent variable is measured; controlled variables are kept constant; a control group provides a baseline.

Key principles. Scientific claims must be testable and open to being shown wrong (falsifiable) [3]. Science changes as evidence accumulates, and major shifts in understanding sometimes occur [4]. Peer review, replication and transparent reporting help correct errors.

Review: In an experiment testing how light affects plant growth, identify the independent and dependent variables. (Answer: the amount of light is independent; plant growth is dependent.)