Topic
Algebra
Numbers with names. Letters stand in for unknowns, balance laws keep both sides honest, and graphs make every equation visible.
Try algebra in 10 seconds
How many were in the box?
Some apples in a box, plus 3 more on top. Total of 8 apples.
Box
x = 2
apples
+ 3 = 8
Your total
5
needs 8
Algebra: write it as x + 3 = 8, subtract 3 from both sides.
Algebra in two sentences
Algebra is what arithmetic looks like when you don't yet know all the numbers. You replace the unknown with a letter, write down the relationship, and use balance laws to find what the letter has to be.
Suggested path
The basics
Letters for unknowns, the equals sign as a balance, and the moves you keep using.
Introduction
Letters stand in for unknown numbers. The first idea — and why it works.
Substitution
Swap a letter for a number. The simplest move in algebra.
Expressions
Combine like terms — simplify with a tap.
Equations
Balance both sides of a scale and solve for the unknown.
Inequalities
Less-than, greater-than, and number-line shading.
Exponents & roots
Repeated multiplication, its inverse, and the rules that hold them together.
Simplifying & ratios
Reshape an expression without changing its value. Compare two ratios.
Polynomials & factoring
Multi-term expressions: how to grow them, how to break them apart.
Functions & graphs
Rules that turn one number into another — and the pictures of those rules.
Apply it
Turn sentences into equations and patterns into rules.