Scientific investigation is a careful way of answering questions using experiments.
We identify variables: the one we change (manipulated), the one we keep the same (constant), and the one we measure (responding). Physical quantities are measured in SI units — length in metres (m), mass in kilograms (kg), time in seconds (s).
Remember
- Change one variable, keep the rest constant, measure the result.
- SI units: metre (m), kilogram (kg), second (s).