What you’ll learn5 learning objectivesChoose one objective for a focused lesson, or study the complete topic.22.3.1Numerical and algebraic calculations• Add, subtract, multiply and divide; use decimals, fractions, ratios, reciprocals, percentages, percentage change and standard form; round to appropriate decimal places or significant figures; use direct and inverse proportion; solve simple equations and substitute quantities into formulas.Syllabus objective22.3.2Geometry, measurement and biological scales• Convert units including cm³ and dm³, mg, g and kg, and μm, mm, cm and m; use areas and volumes of common shapes, rulers, estimates, scale diagrams and surface-area-to-volume ratios; select appropriate units.Syllabus objective22.3.3Graphs, charts and statistics• Draw and interpret line graphs, bar charts, pie charts and equal-interval histograms; interpolate and extrapolate; determine gradients and intercepts with units; select scales and axes; recognise proportionality; calculate means and ranges; use simple probability.Syllabus objective22.3.4Record readings and tabulated data• Record readings to the precision of the instrument with correct units and significant figures; head table columns with quantity and unit separated by a solidus; omit units from table bodies.Syllabus objective22.3.5Plot, analyse and present biological data• Plot independent and dependent variables on correctly labelled axes using sensible scales; mark points accurately; draw justified best-fit lines or curves; read by interpolation or extrapolation; produce clear biological drawings and appropriate pie or bar charts.Syllabus objective