Scientific Skills and Processes
What you must understand
Science is a way of finding out, not a list of facts to memorise. Candidates must know the sequence of a fair investigation: identifying a problem, forming a hypothesis, planning a controlled experiment, collecting and recording data, presenting results in tables and graphs, drawing conclusions, and evaluating the method. You must be able to identify the independent variable (what you change), the dependent variable (what you measure), and the controlled variables (everything kept the same). Know the difference between observation and inference, and between accuracy and reliability.
Traps that appear in questions
- Naming the dependent variable as the thing you change. The dependent variable is always the one you measure.
- Saying a result is "proved" after one trial. Repeat readings to improve reliability.
- Confusing a hypothesis with a prediction or a guess; a hypothesis must be testable.
- Forgetting units on table headings and axes.
- Reading a graph as if the line between plotted points were measured data.
- Describing a conclusion as "the experiment worked" instead of answering the original question.
Rule of thumb and worked example
Use the C-M-C rule: Change one thing, Measure one thing, Control the rest.
Example: A learner waters bean seedlings with different amounts of water to see which grows tallest. The amount of water is the independent variable; final height is the dependent variable; soil type, light, pot size and number of seeds are controlled variables. Measure height with a ruler in centimetres, record in a table, average repeat plants, then plot a bar or line graph with a titled axis for each variable. The conclusion states the relationship found, not merely that growth occurred.