Foundations of Scientific Inquiry
The Foundations of Scientific Inquiry domain tests experimental design, measurement and error, data display, and the use and limits of models. Expect items that ask you to identify variables and controls, select units, read the Earth Science Reference Tables (ESRT), and compute density, gradient, or rate of change.
Designing a controlled investigation
- The independent variable is manipulated; the dependent variable is measured.
- Constants are held fixed; a control group receives no treatment.
- Repeat trials and use adequate sample size; one trial cannot establish a pattern.
- A hypothesis must be testable and falsifiable. Data can support or refute it, never "prove" it.
Measurement and derived quantities
- Precision is repeatability; accuracy is closeness to the accepted value.
- Percent deviation = (measured − accepted) ÷ accepted × 100.
- Density = mass ÷ volume. Gradient = change in field value ÷ distance. Rate of change = change in value ÷ time.
- Convert to consistent units before calculating, and report units with every answer.
Graphs and models
- Direct relationships rise together; inverse relationships move oppositely; cyclic data repeat.
- Match the graph to the data: line graphs for continuous change, bar graphs for categories.
- Extrapolating beyond the data range is uncertain. Models are simplifications and are revised with new evidence.
Worked example
A specimen has mass 54.0 g and volume 20.0 cm³, so density = 54.0 ÷ 20.0 = 2.70 g/cm³. The accepted value is 2.65 g/cm³. Percent deviation = |2.70 − 2.65| ÷ 2.65 × 100 ≈ 1.9%, an accurate result. If the volume were misread as 18.0 cm³, the density would be 3.00 g/cm³ and deviation ≈13%: a small measurement error in the denominator produces a large error in the result.
Traps that cost marks
- Calling a result "proven" instead of supported.
- Treating repeated, consistent measurements as accurate when they are only precise.
- Confusing correlation with causation.
- Omitting units or mixing grams and kilograms.