Middle & high-school math · self-study
Learn math from first principles
Most math courses hand you formulas and ask you to practice them. This one shows you where those formulas come from. Every result is proved from scratch, and the proof is the lesson.
- Why proofs
- Because knowing why a rule works is what lets you use it in a new situation. Memorizing that a negative exponent means "flip it to the denominator" is not the same as understanding that a negative exponent is just the subtraction rule applied one step past zero, and once you see that, the rule is obvious rather than arbitrary.
- How lessons work
- Every lesson opens with a motivation (the problem the idea actually solves), then builds the result from scratch. Worked examples follow, then a few in-lesson checkpoint questions, then a common-mistakes callout. There are no hand-waves. If a step looks like it comes out of nowhere, that's a bug.
- Practice
- Five sets of 12 questions per lesson, ordered by difficulty. Each question has a full worked solution you can reveal whenever you want. No timer, no score pressure, no account required. Your answers are saved in the browser.
How the subjects connect
Geometry and Algebra II can be taken in either order. Statistics and Probability does not require Precalculus or Calculus.
Subjects
Available now
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Pre-Algebra
The foundation for all of middle- and high-school math: arithmetic, integers, fractions, decimals, exponents, ratios, and a first look at algebra and geometry, all from first principles.
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Algebra I
Algebra in full, picking up where Pre-Algebra ends: linear equations and systems, graphing, inequalities, quadratics and complex numbers, functions, exponentials and logarithms, and sequences and series, every step from first principles.
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Algebra II
A full second course in algebra: functions and their graphs, systems, quadratics and complex numbers, polynomial and rational functions, radicals, exponential and logarithmic functions, sequences and series, conic sections, and a first look at probability, all from first principles.
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Coming soon
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Geometry
Coming soonPlane and solid geometry built on proof: lines and angles, congruent and similar triangles, right-triangle trigonometry, quadrilaterals and polygons, circles, area, surface area and volume, transformations, coordinate geometry, and compass-and-straightedge constructions, every result reasoned from first principles.
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Precalculus
Coming soonThe bridge to calculus: functions and their transformations, polynomial and rational functions, exponentials and logarithms, trigonometry and its identities, polar and parametric curves, complex numbers and vectors, matrices, conic sections, sequences and series, and a first look at limits, all from first principles.
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Calculus AB
Coming soonA first single-variable calculus course, matching AP Calculus AB: limits and continuity, the derivative and its rules, contextual and analytical applications of differentiation, integration and the Fundamental Theorem of Calculus, separable differential equations, and applications of the integral, developed from first principles.
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Calculus BC
Coming soonThe full single-variable calculus course, matching AP Calculus BC: everything in Calculus AB plus advanced integration techniques, Euler's method and logistic models, arc length, parametric, polar, and vector-valued functions, and infinite sequences and series including Taylor and Maclaurin series, all from first principles.
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Statistics and Probability
Coming soonA first course in data and inference, matching AP Statistics: exploring one- and two-variable data, designing studies, counting and probability, random variables and distributions, the normal model, sampling distributions, confidence intervals, and significance tests, reasoned from first principles.
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Editorial standards
Lessons are developed with AI assistance and reviewed for mathematical correctness, clarity, prerequisite consistency, and practice-answer accuracy before publication.