What you’ll learn7 learning objectivesChoose one objective for a focused lesson, or study the complete topic.P5.1Defining the problem and predictionUse the context to state a relevant prediction in words or as a sketch graph, link it to a hypothesis, identify independent and dependent variables and identify key variables that must be standardised.Syllabus objectiveP5.2Planning experimental methodsDescribe how to vary the independent variable; measure independent and dependent variables accurately and to appropriate precision; standardise key variables; choose suitable volumes and concentrations; prepare different concentrations by serial dilution or proportional dilution; include controls; sequence the method logically; plan how to collect results.Syllabus objectiveP5.3Assessing result quality, validity and riskDescribe how to judge result quality using anomalies, spread, standard deviation, standard error or 95% confidence intervals; assess validity using accuracy and repeatability; prepare a simple risk assessment considering hazard severity and probability; state precautions to reduce risk.Syllabus objectiveP5.4Dealing with experimental dataUse tables and graphs to show key quantitative data; draw suitable graphs with independent variable on the x-axis and dependent variable on the y-axis; add confidence-limit error bars where required; choose calculations including means, percentages, percentage gain or loss and rates of change.Syllabus objectiveP5.5Statistical tests and data types in practical contextsUse standard deviation, standard error or error bars to judge likely significance; choose and carry out appropriate statistical tests from the mathematical requirements; justify the test; state a null hypothesis; recognise categoric, ordinal and continuous data.Syllabus objectiveP5.6Conclusions from raw and processed dataSummarise main conclusions; identify key points in raw data, processed data, graphs and statistical results; discuss how far a hypothesis is supported; give scientific explanations; make further predictions and hypotheses.Syllabus objectiveP5.7Evaluation of investigationsIdentify anomalous values and possible explanations; assess replication, independent-variable range and intervals, measurement method and control of variables; judge validity, how well data test the hypothesis and confidence in conclusions; suggest improvements that increase confidence.Syllabus objective