IGCSE Science Command Words

Determine an answer's required scope from the command word, mark allocation, supplied information and answer space without assuming that every mark requires a separate sentence.

Set out equations, substitutions, units, significant figures and rounding for “calculate”, “determine”, “estimate” and “show that” questions.

Answer “deduce”, “suggest” and “predict” questions by combining known science with information supplied in an unfamiliar context.

Audit a topic against the linear Pearson Edexcel International GCSE Science (Double Award) 4SD0 specification and the matching CGP guide, excluding modular-course material.

Convert specification statements and corrected mistakes into focused question-and-answer flashcards.

Schedule active recall and spaced reviews so flashcards test memory rather than recognition.

Classify topic questions by recurring demand, command word, calculation type and mark-scheme pattern.

Mark answers against distinct marking points, accepted alternatives and required scientific vocabulary.

Maintain an error log that distinguishes knowledge gaps, command-word errors, calculation errors and careless mistakes and assigns a corrective action to each.

Apply time-per-mark, targeted checking and no-notes correction techniques to a timed sample section.

Construct a September–November specification, CGP, flashcard and topic-question schedule and a December–April timed past-paper cycle, reserving May for targeted correction and exam readiness.

Classify plants, animals, fungi, protoctists and bacteria using their defining features, and distinguish viruses from cellular organisms.

Compare plant, animal and bacterial cells from diagrams and descriptions.

Explain how the structures of major cell components enable their functions.

Relate specialised cells, tissues, organs and organ systems using biological examples.

Relate carbohydrates, proteins, lipids, vitamins, minerals, fibre and water to their roles in a balanced diet.

Use the Benedict’s, iodine, Biuret and emulsion tests to identify biological substances from observations.

Explain enzyme action and predict how temperature and pH affect enzyme-controlled reactions.

Compare diffusion, osmosis and active transport and apply each process to unfamiliar biological situations.

Use the word and balanced chemical equations for photosynthesis to interpret limiting-factor data.

Relate leaf structures to photosynthesis and gas exchange.

Explain how mineral uptake, xylem transport, transpiration and phloem translocation support a plant.

Explain mechanical and chemical digestion and relate villus structure to nutrient absorption.

Compare aerobic and anaerobic respiration using equations, energy transfer and biological examples.

Explain ventilation and gas exchange using the structures and concentration gradients involved.

Trace double circulation and relate the structures of the heart, blood vessels and blood components to their functions.

Explain how carbon dioxide and urea are produced and excreted from the human body.

Compare nervous and hormonal coordination, including reflexes and the control of blood glucose and body temperature.

Compare sexual and asexual reproduction and explain pollination, fertilisation and seed formation in flowering plants.

Explain the roles of reproductive organs, hormones, fertilisation and the placenta in human reproduction.

Use genetic vocabulary and predict monohybrid inheritance outcomes using genetic diagrams and pedigrees.

Explain variation, mutation, natural selection, evolution and selective breeding using linked causal steps.

Analyse food chains, food webs, pyramids, nutrient cycles, population changes and sampling data.

Interpret field-sampling and population data and evaluate specified human impacts on ecosystems.

Evaluate the uses, benefits and risks of microorganisms in food production, controlled crop production, cloning and genetic modification.

Use the particle model to explain states of matter, changes of state, diffusion and heating or cooling curves.

Select and explain filtration, crystallisation, simple distillation, fractional distillation and chromatography for separating mixtures.

Determine numbers of protons, neutrons and electrons in atoms, ions and isotopes from atomic and mass numbers.

Use electron configurations to explain an element’s position and broad chemical behaviour in the periodic table.

Write chemical formulae and balance symbol equations, including state symbols.

Explain ionic bonding and relate giant ionic structures to their physical properties.

Explain covalent bonding and relate simple molecular and giant covalent structures to their physical properties.

Explain metallic bonding and relate metallic structure to conductivity, malleability and melting point.

Calculate relative formula mass and use the mole relationship between mass, amount and molar mass.

Use balanced equations and mole ratios to calculate reacting masses and percentage yield.

Determine empirical formulae from composition data and calculate solution concentrations using appropriate units.

Use the reactivity series to predict displacement, extraction and reactions with water or dilute acids.

Use pH, indicators and ionic equations to explain acids, alkalis and neutralisation.

Select and describe suitable methods for preparing pure, dry samples of soluble and insoluble salts.

Explain patterns in Groups 1, 7 and 0 using atomic structure and supplied evidence.

Identify common gases, cations and anions using specified qualitative tests and observations.

Explain atmospheric composition and use combustion equations to relate common pollutants to their environmental effects.

Interpret energy-level diagrams and bond-energy data for exothermic and endothermic reactions.

Explain collision theory and predict how concentration, pressure, surface area, temperature and catalysts affect reaction rate.

Predict the effects of changing conditions on reversible reactions at equilibrium.

Predict products of electrolysis and write half-equations for molten and aqueous ionic compounds.

Explain how fractional distillation separates crude oil into fractions with different uses and properties.

Explain cracking and use displayed formulae to represent alkene reactions and the bromine-water test.

Represent addition polymerisation and evaluate disposal and environmental problems associated with synthetic polymers.

Calculate speed and acceleration and distinguish scalar distance and speed from vector displacement and velocity.

Interpret and construct distance–time and velocity–time graphs, including gradients and areas.

Apply resultant force and Newton’s laws to explain changes in motion.

Calculate weight and explain the distinction between mass, weight and gravitational field strength.

Explain how friction, drag, reaction time and braking affect stopping distance and terminal velocity.

Apply the principle of moments and Hooke’s law to balanced and elastic systems.

Track energy stores and transfers and calculate efficiency using conservation of energy.

Calculate work done and power in mechanical situations.

Distinguish charge, current, potential difference and resistance and select suitable meters for measuring them.

Apply charge, current, potential-difference and resistance equations to series and parallel circuits.

Calculate electrical power and energy transferred using circuit data and SI units.

Explain mains electricity, earthing, fuses, circuit breakers and insulation in terms of electrical safety.

Calculate density and pressure and apply them to solids, liquids and gases.

Use the particle model and Kelvin scale to explain changes of state, gas pressure and thermal-energy changes.

Explain conduction, convection and radiation and evaluate methods of reducing unwanted thermal transfer.

Compare renewable and non-renewable energy resources using reliability, environmental impact and cost evidence.

Calculate wave speed, frequency, wavelength and period and interpret transverse and longitudinal wave diagrams.

Apply reflection, refraction and total internal reflection to ray diagrams and practical situations.

Compare the regions of the electromagnetic spectrum by order, uses and hazards.

Explain magnetic fields, electromagnets and the motor effect using field directions and forces.

Explain electromagnetic induction and apply transformer relationships to electricity transmission.

Compare alpha, beta and gamma radiation by nature, penetration, ionisation and behaviour in fields.

Determine half-life from graphs or numerical data and apply it to activity and safety questions.

Explain the production, transmission and detection of sound and relate pitch and loudness to frequency and amplitude.

Identify independent, dependent and control variables in Biology, Chemistry and Physics investigations.

Write a repeatable experimental method containing suitable apparatus, measurements, controls and safety precautions.

Select measuring equipment using its range and resolution and justify the choice.

Construct results tables with headings and units, calculate means and identify anomalous results.

Plot data using suitable scales and draw an appropriate line or curve of best fit.

Determine relationships, gradients and intercepts from graphs and relate them to the investigated science.

Distinguish exact plotting from “draw”, “sketch” and “complete” tasks and complete partially supplied diagrams, graphs and tables.

Answer “evaluate”, “discuss” and “justify” questions using evidence, limitations, conclusions and specific improvements.