Revision guides. Short and clear.
Each guide explains one big GCSE topic, with a worked example and a quick quiz. Then practise it properly on OmniEx.
ChemistryMoles explainedWhat a mole is, the formula n = m ÷ Mr, and how to use it.ChemistryHow to balance chemical equationsStep-by-step method for balancing equations, with worked examples.ChemistryIonic vs covalent bondingThe difference between ionic and covalent bonds and the properties they give.ChemistryRates of reaction and collision theoryWhat changes the speed of a reaction and why, using collision theory.ChemistryElectrolysis explainedHow electrolysis splits ionic compounds, which ions go where, and OIL RIG.PhysicsOhm's law: V = I × RVoltage, current and resistance, with worked examples.PhysicsWaves: transverse, longitudinal and v = f λWave types, key words and the wave equation.PhysicsForces, motion and Newton's lawsResultant force, F = m × a and Newton's three laws.BiologyPhotosynthesis explainedThe equation, where it happens and what limits its rate.BiologyAnimal and plant cellsCell structures, their jobs and the difference between eukaryotes and prokaryotes.MathsPythagoras' theoremHow to find any side of a right-angled triangle.MathsPercentages: of, increase, decrease and reverseEvery type of GCSE percentage question with multipliers.
Element facts
Every one of the 118 elements has its own page. Start at hydrogen or explore the interactive periodic table.