Practical assessment skills
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Paper 3 Advanced Practical Skills
P3.1Successful collection of data and observations
Set up apparatus, follow written or diagram instructions, collect an appropriate quantity of data, make observations including subtle differences in colour, solubility or amount, and use common laboratory apparatus such as pipettes, burettes, measuring cylinders and thermometers.
P3.2Measurement quality and concordancy
Make accurate and consistent measurements and observations, including concordant titres within 0.10 cm3, precise colour descriptions and readings that match the precision of the apparatus and materials provided.
P3.3Decisions about measurements and observations
Decide how many tests or observations to perform, choose a suitable range and distribution of measurements, identify when repeats or confirmatory tests are needed, replicate suspected anomalies and select reagents to distinguish between given ions.
P3.4Recording data and observations
Present numerical data, values or observations in a single results table with accepted scientific headings and units; record raw readings to consistent precision; record qualitative observations clearly, including no change where relevant.
P3.5Calculations, reasoning and significant figures
Show working and key reasoning steps in calculations; use the correct number of significant figures, normally the same as or one more than the smallest number of significant figures in the data used.
P3.6Data layout, tables and graphs
Prepare tables before collecting data; plot appropriate variables on labelled axes; choose scales that use the grid well; plot points accurately with crosses or circled dots; draw best-fit lines or smooth curves; identify anomalous points.
P3.7Interpreting data and drawing conclusions
Describe patterns and trends in tables, graphs and observations; calculate means, percentages, rates, concentrations, molar masses or gas volumes; find unknown values from coordinates, intercepts or gradients; draw conclusions and make scientific explanations linked to theory.
P3.8Errors, uncertainty, improvements and extensions
Evaluate control variables; distinguish systematic and random errors; identify significant sources of error; state actual or percentage uncertainty; suggest realistic modifications to improve accuracy or observations; extend an investigation to answer a new question.
P3.9Quantitative practical procedures
Carry out and interpret titrations, rates experiments, gravimetric experiments, thermometric experiments and gas volume experiments, including rough titrations, concordant titres, heating to constant mass, temperature-change measurements and gas collection over water.
P3.10Qualitative analysis notes and tests
Use qualitative analysis notes for cation, anion, gas and iodine tests; record observations safely and completely; use excess reagent where required; identify gases from effervescence; interpret organic tests such as Fehling’s, Tollens’, alkaline iodine and acidified manganate(VII).
P3.11Apparatus, materials, hazards and safety
Be familiar with standard practical apparatus, common reagents, indicator ranges, hazard codes and safe laboratory practice; understand that confidential instructions specify exact materials and that safety responsibility includes risk-aware handling and disposal.