Math, one step at a time.

Free lessons from basic review to college calculus, where every rule comes with examples worked line by line, practice problems with solutions, and a quick check to see if it clicked.

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Factor completely

x² − 9
= x² − 3²9 is a perfect square
= (x + 3)(x − 3)difference of squares
check: x² − 3x + 3x − 9 = x² − 9

Where do you want to start?

Pick the path closest to you: the courses are already in the right order.

Start from the basics

Review from the ground up

Operations, fractions and percents: everything you need to reach algebra without gaps.

Start with Math basics

High school

Algebra 1 through precalculus

The high school sequence in order: algebra, geometry, trigonometry, exponentials and logarithms.

Start with Algebra 1

College prep

Before college or a placement test

The review that placement tests expect: inequalities, radicals, logarithms, trigonometry, lines and conic sections.

Start with Algebra 2

College

Calculus and statistics

Limits, derivatives, curve sketching and integrals, then probability and statistics for intro courses.

Start with Calculus

Courses, in the order you learn them

Follow them from the start or jump straight to the topic you need.

Math basics

Elementary math review: multi-digit operations, multiplication facts, long division, units, perimeter and area.

Review, all ages 6 lessons about 1 hour
Pre-algebra

Integers, fractions, exponents, percentages, ratios and the order of operations.

Ages 11–14 15 lessons about 2 hours
Algebra 1

Monomials, polynomials, special products, factoring, rational expressions and linear equations.

Ages 14–16 18 lessons about 3 hours
Algebra 2

Inequalities, systems of equations, radicals, quadratic equations and inequalities.

Ages 15–17 16 lessons about 3 hours
Geometry

Triangles, quadrilaterals, circles, area, the Pythagorean theorem and similarity.

Ages 14–16 14 lessons about 3 hours
Coordinate geometry

The coordinate plane, lines, parabolas, circles, ellipses and hyperbolas.

Ages 15–17 10 lessons about 2 hours
Trigonometry

Sine, cosine and tangent, identities, trigonometric equations and solving triangles.

Ages 16–18 11 lessons about 2 hours
Exponentials and logarithms

Exponential and logarithmic functions, their properties, equations and inequalities.

Ages 16–18 9 lessons about 2 hours
Calculus

Functions, limits, continuity, derivatives, curve sketching and integrals.

Ages 17–18 and college 12 lessons about 3 hours
Probability and statistics

Counting, probability, mean, variance and distributions.

Ages 15–18 and college 10 lessons about 2 hours

What a lesson looks like

Every page follows the same layout, so you always know where to look.

The rule, in plain words: First the idea, then the formula. Key definitions sit in their own box so you can find them at a glance.
Examples on graph paper: One step per line, with the reason next to it. The most common mistakes are flagged in red.
Practice and quick checks: Try each problem yourself and open the solution only when you're done. The quick check tells you right away if you've got it.