General

• independent variable - the variable that is changed
• dependent variable - the variable that is measured
• controlled variable - the variables that are kept the same
• Random errors are due to things you have no control over, such as a change in room temperature whilst you were collecting the results and reaction time when starting and stopping a stopwatch. Repeating your measurements and finding an average will reduce the effect of random errors.
• Systematic errors are due to problems with the equipment you used. For example, the balances you used may not have been set to zero at the start of the experiment and be out by 0.1 g for every measurement.