Scientific Method, Laboratory Skills and Data Interpretation
What you must understand
Know the steps of the scientific method: observation, question, hypothesis, prediction, experiment, data collection, analysis, conclusion. Understand variables: independent, dependent and controlled. Know the difference between a hypothesis and a theory. Understand experimental design: control group, experimental group, sample size, and the importance of repetition for reliability. In the laboratory, know the correct use of the microscope (magnification, focusing), pipettes, balances and glassware, and safety rules (goggles, handling chemicals, waste disposal). Be able to interpret tables, graphs and charts: identify trends, calculate means, and recognise anomalies.
Traps that appear in questions
- Confusing the independent variable (what you change) with the dependent variable (what you measure).
- Forgetting the control group - without it, you cannot attribute change to the treatment.
- Saying a hypothesis is proven - it is supported or rejected.
- Confusing accuracy (closeness to true value) with precision (consistency of repeated measurements).
- Misreading a graph axis or ignoring units.
Worked example
A student tests whether light affects plant growth. Independent variable: light exposure. Dependent variable: plant height. Controlled variables: water, soil, temperature. The control group receives no light change. Rule of thumb: change one thing, measure one thing, keep everything else constant.