What you’ll learn6 learning objectivesChoose one objective for a focused lesson, or study the complete topic.13.3.1Numerical and algebraic calculations• Use arithmetic, decimals, fractions, percentages, ratios, reciprocals and standard form; round only final answers and use decimal places and significant figures appropriately; use positive whole-number indices, consistent units, simple equations and direct or inverse proportion.Syllabus objective13.3.2Geometry, measurement and unit conversion• Use common geometrical terms, select suitable units and convert between units including cm³ and dm³, mg, g and kg, J and kJ, and Pa and kPa.Syllabus objective13.3.3Graphs, charts and statistics• Draw and interpret graphs and charts; interpolate and extrapolate; determine gradients and intercepts; select suitable scales and axes; recognise direct proportionality and calculate means.Syllabus objective13.3.4Record readings and tabulated data• Read instruments to half a smallest division where appropriate; record precision, units, repeated readings and significant figures correctly; use quantity/unit table headings and express ratios as x : y.Syllabus objective13.3.5Plot and analyse chemical data• Plot variables on labelled axes with sensible scales; mark points accurately; draw best-fit lines or curves while treating anomalies appropriately; read values, intercepts and gradients using suitably large triangles.Syllabus objective13.3.6Extended graph gradients• Determine the gradient of a curve by drawing a tangent.Syllabus objective