P5.1—Defining the experimental problem

A sound investigation begins with an aim and prediction, identifies the independent and dependent variables, fixes control variables, and selects a safe procedure and suitable apparatus.

Write the prediction in words or as a graph with a stated direction or relationship. Choose a range that can reveal the pattern and a measurement method that responds to the dependent variable.

To test how concentration affects initial rate, vary concentration, measure a time-based rate, hold temperature and total volume constant, and predict how the graph should change.

“Investigate the effect of X” is not a complete aim until the measured outcome, controls and feasible range are specified.