Foundations of Scientific Inquiry
What the exam tests
Scientific inquiry questions ask you to design controlled experiments, evaluate measurement quality, and handle units and significant figures with confidence. Expect variables, controls, graphing, uncertainty, and error analysis rather than vocabulary recall.
Core rules
- Identify independent, dependent, and controlled variables; a valid experiment changes one variable at a time and includes a control group when a comparison is needed.
- SI units: length m, mass kg, amount mol, temperature K, time s. Convert with dimensional analysis and cancel units.
- Significant figures: multiplication/division keeps the least number of sig figs; addition/subtraction keeps the least number of decimal places. Exact counts and definitions have infinite sig figs.
- Accuracy is closeness to true value; precision is reproducibility. Percent error = |experimental − accepted| / accepted × 100%.
- A linear graph's slope carries units of y per x; use it to extract a constant.
Worked example
A sample has mass 12.34 g and volume 4.2 mL. Density = 12.34 g / 4.2 mL = 2.938... g/mL. The volume has two significant figures, so report 2.9 g/mL. If the accepted density is 3.0 g/mL, percent error = |2.9 − 3.0| / 3.0 × 100% = 3.3%, limited by the two-sig-fig density.
Traps
Mixing sig-fig rules for multiplication and addition; treating a precise but biased measurement as accurate; cubing a unit conversion factor without cubing the number; ignoring uncertainty in a slope; and confusing a control group with a controlled variable.