Scientific Questions and Investigations

Objective: Form a question that can be addressed with evidence and write a testable prediction.

A scientific question can be investigated with observations or measurements. A hypothesis is a tentative, testable explanation; a prediction states what is expected under particular conditions if the explanation is useful. A prediction is not the same thing as a hypothesis. Scientific investigations may be experimental or observational, and their design depends on the question and practical constraints.

Objective: Identify changed, measured, and controlled factors.

In a controlled experiment, the independent variable is the factor deliberately changed, and the dependent variable is the measured response. Controlled variables are held as consistent as practicable so comparisons are interpretable. A control or comparison group provides a reference, but not every valid scientific study has a manipulable control group. Random assignment and repeated trials can reduce some sources of bias and chance variation.

Objective: Explain repetition, sample size, limits, and responsible handling of evidence.

Repeated measurements reveal variability and can improve estimates. Sample size, randomization, measurement accuracy, and controls influence how confidently a result can be interpreted. Correlation alone does not establish causation, and an uncontrolled difference may be a confounding factor. Scientists report methods and limitations, preserve records, and avoid inventing or selectively hiding results. Safety and ethical review constrain what investigations are appropriate.