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.
- Domain and Range: The Inputs and Outputs of a Function
What domain and range mean, how to find them from a graph, a table or an equation, and why some inputs have to be excluded.
- Function Notation: What f(x) Actually Means
Understand f(x) as a name and an input rather than multiplication, how to evaluate it, and how to read statements like f(3) = 7 in context.
- How to Graph Linear Equations
Graph a line three ways — from slope-intercept form, from intercepts, or from a table — and understand why every point on the line is a solution.