Fractions explained: add, multiply, divide and simplify
Learn how fractions work, with step-by-step examples for adding, multiplying, dividing and simplifying them. Ideal for KS3 and middle school.
KS3Middle SchoolStuck on a topic? Learn it step by step.
Free study guides and revision notes for GCSE, A-Level, AP and high school. Clear explanations, worked examples and practice questions with answers, all in plain English.
Circle theoremsPythagoras' theoremSimultaneous equationsQuadratic equationsPhotosynthesisMitosisReactivity series
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Browse all 158 guides →Photosynthesis explained: equation, process and limiting factors
Learn how plants make glucose and oxygen from light, water and carbon dioxide, with the equation, limiting factors and practice questions.
KS3GCSEMiddle SchoolHigh School+1Atoms and the periodic table: protons, neutrons, electrons
Learn atomic structure, atomic and mass number, isotopes and how the periodic table is organised, with worked examples.
KS3GCSEMiddle SchoolHigh SchoolNewton's laws of motion explained with worked examples
Learn Newton's three laws, use F = ma and understand inertia and action-reaction pairs, with worked examples and practice questions.
KS3GCSEMiddle SchoolHigh SchoolParts of speech: noun, verb, adjective, adverb and more
Learn the eight parts of speech with examples, and see how the same word can change class depending on how it is used.
KS3Middle SchoolCauses of World War One: MAIN causes and the trigger
Learn the long-term causes of the First World War (militarism, alliances, imperialism, nationalism) and how the 1914 assassination set it off.
GCSEA-LevelHigh SchoolAPThe water cycle: evaporation, condensation and precipitation
Follow water from sea to sky to land, learn each stage of the water cycle and see how people affect it.
KS3Middle SchoolHow AI works: machine learning and chatbots for students
Understand machine learning, training data and large language models, plus the limits of AI and how to use it responsibly.
KS3GCSEMiddle SchoolHigh SchoolActive recall: the best way to revise (with examples)
Learn why testing yourself beats rereading, and four simple ways to use active recall: flashcards, blank-page recall and practice questions.
KS3GCSEA-LevelMiddle School+3Digital SAT explained: sections, timing and adaptive modules
How the Digital SAT works: the two sections, four modules, timing and how adaptive testing affects your second module.
Admissions testsHigh SchoolHow each guide helps you revise
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A short explanation in plain English, with the key formulas and the mistakes students make most often.
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Follow worked examples step by step, then answer five practice questions. Every answer is explained.
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