Scientific enquiry, practical skills and the nature of science
The Scientific enquiry, practical skills and the nature of science domain tests how you plan, carry out and evaluate investigations, not just recall facts. Questions ask you to identify variables, choose apparatus, record data, process graphs and judge whether a conclusion is supported.
Core ideas
- In a fair test, change one independent variable, measure the dependent variable and keep all other variables controlled.
- Accuracy is closeness to the true value; precision is how closely repeated readings agree. Repeat readings and calculate a mean to improve reliability.
- Choose apparatus to match the required precision: a ruler to 1 mm, a measuring cylinder to the nearest division, a balance for mass.
- Record raw data in a table with units in the headings. Plot the independent variable on the x-axis and the dependent variable on the y-axis.
- Identify anomalies and exclude them from a mean, but report them. A line of best fit shows the trend; do not force it through the origin unless the physics says it should.
- Evaluate risks and use controls: goggles, heat-proof mat, clamp stand, fume cupboard where needed.
Worked example
A student hangs masses from a spring and measures extension. Independent variable: load; dependent: extension; controlled: same spring, same ruler position, no stretching beyond the elastic limit. Readings: 0, 2, 4, 5, 9 cm for loads 0, 1, 2, 3, 4 N. The 5 cm reading is anomalous; repeat it. Mean extension per newton from the reliable points is about 2 cm/N. The conclusion is that extension is proportional to load within the elastic limit.
Traps
Confusing accuracy with precision; changing two variables; forgetting units; drawing a curve through an anomaly; saying a result is 'proved' from one trial.