Math lessons that are actually complete
Every lesson explains the concept, shows why it works, walks through examples, and gives you practice problems with every solution step. Free, on one page, aligned to what US schools actually teach.
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Every lesson is tagged to the Common Core standards it teaches, and shows the full official wording — not just a code. Browse all 509 standards to find lessons aligned to what you are teaching.
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Latest lessons
- How to Solve Absolute Value Equations
Solve absolute value equations by splitting into two cases, why two answers appear, when there is no solution, and how absolute value inequalities differ.
- Completing the Square, Step by Step
Learn completing the square: why the method works geometrically, how to handle a leading coefficient, and how it produces vertex form and the quadratic formula.
- How to Solve Compound Inequalities (AND and OR)
Solve compound inequalities joined by AND or OR, graph the solution on a number line, and tell which combinations give no solution or every number.
- How to Solve Literal Equations and Rearrange Formulas
Rearrange a formula to solve for any variable using the same inverse operations you use on numbers, with worked examples from geometry, physics, and finance.
- How to Solve Multi-Step Equations
Solve multi-step equations by distributing, combining like terms, then undoing operations in reverse order, with worked examples and practice problems.
- How to Solve Multi-Step Inequalities
Solve multi-step inequalities by distributing, combining like terms, and undoing operations in reverse order, including when to flip the inequality sign.