Study guides that actually teach
In-depth, free explainers on the subjects and exams you're tackling — then study them with the full AI Matrx toolkit.
Study guides & explainers
Clear, comprehensive content on the topics you're studying — free to read, easy to turn into flashcards, quizzes, and audio.
AP Biology: The Big Ideas, Explained
The four Big Ideas and eight units of AP Biology, how the exam scores reasoning over recall, and a plan to master both content and science practices — with free certified decks.
SAT Math: The Complete Study Guide
How the digital SAT Math section is built, the four content domains it tests, and a proven plan to raise your score — with free certified practice decks.
GRE Verbal: The Complete Strategy Guide
The three GRE Verbal question types, the reasoning strategies that beat trap answers, and a vocabulary plan that sticks — with free certified decks.
Cell Structure and Function, Explained
A clear walkthrough of the cell — the basic unit of life — covering the major organelles, the difference between prokaryotic and eukaryotic cells, and how structure drives function.
Supply and Demand, Explained
How prices are set in a market — the law of demand, the law of supply, how they meet at equilibrium, and what makes the whole curve shift — the single most important model in economics.
Newton's Three Laws of Motion, Explained
The three laws that govern how objects move — inertia, force equals mass times acceleration, and action-reaction — with the intuition, the equations, and the everyday examples that make them stick.
Solving Linear Equations, Explained
A step-by-step guide to solving for an unknown in a linear equation — isolating the variable, balancing both sides, clearing fractions, and checking your answer — the foundation of all of algebra.
The French Revolution: Causes and Timeline
Why France's old order collapsed after 1789 — the financial crisis, social inequality, and Enlightenment ideas that lit the fuse — and a clear timeline from the Estates-General through the Terror to Napoleon.
The Cell Cycle and Mitosis, Explained
How a single cell becomes two identical daughter cells — the phases of the cell cycle, the stages of mitosis, the checkpoints that keep division under control, and why failures lead to cancer.
Photosynthesis, Explained
How plants, algae, and some bacteria turn sunlight, water, and carbon dioxide into sugar and oxygen — the light-dependent reactions, the Calvin cycle, and why this single process underwrites nearly all life on Earth.
AP World History: The Complete Study Guide
What AP World History covers, how the exam is structured, the nine units and their themes, and the fastest way to master it — from the 1200 CE starting point to the modern era.