Scientific Investigation
Planning and Running a Fair Test
Scientific investigation is about asking a question that can be answered by measurement, then designing a method that isolates one factor. The independent variable is the one you deliberately change; the dependent variable is the one you measure; control variables are everything else you keep the same so the comparison is fair. Always plan repeated readings, identify how to measure precisely, and state a prediction (hypothesis) that links the two variables.
Recording and Processing Data
Present results in a table with units in the column headings, not beside each number. Plot the independent variable on the x-axis and the dependent variable on the y-axis, label both axes with quantity and unit, and draw a smooth best-fit line rather than joining every dot. Anomalous points (results far from the trend) should be circled or noted, not silently deleted.
Drawing Conclusions
A conclusion answers the original question using the evidence: describe the pattern (as x increases, y increases), quote data, and explain using scientific ideas. Evaluation asks how reliable and valid the data are, and suggests one specific improvement.
Traps to Watch
- Confusing independent and dependent variables when the question reverses the wording.
- Claiming a conclusion "proves" a hypothesis from a single trial.
- Forgetting units, or mixing units within one table.
- Saying "the results were accurate" when you mean precise or repeatable.
Rule of Thumb
Write the method as a recipe a stranger could follow: change one, measure one, keep the rest the same, repeat three times, average. If your plan cannot be repeated by someone else, it is not yet a fair test.