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Algebra (Mathematics Lesson)

What Is Algebra?

Algebra is using letters (or other symbols) to represent numbers.

The letters (or other symbols) can be combined with numbers and operators (add, subtract, multiply, divide) to make an expression.

An equation that uses algebra is called an algebraic equation. (Note: algebraic is the adjective for algebra.)

Why Is Algebra Useful?

Algebra is useful because sometimes you need to use mathematics to solve puzzles.

Sometimes there is a number that you don't know yet. This number is a variable or an unknown.

In the puzzle above, it says "some number plus 1 equals 2".

You can figure out what the number is by representing it by a letter (such as x) or another symbol. By putting this letter in an algebraic equation, the equation can be solved, and you can find out what the unknown is.

The ?  is represented by an x. When the algebraic equation is solved, you find out what x is:

Before, you could only say "some number plus 1 equals 2". Now, you know "1 plus 1 equals 2".

Different Types of Algebraic Equations

There are different types of algebraic equations. They can contain addition, subtraction, multiplication, division, or any combination of them.

Some Algebraic Definitions

Here are some useful definitions that are useful not only in algebra but many other areas of mathematics.

The slider below gives more information about algebraic definitions.
Interactive Test

Algebra comes from the Arabic word 'al-jebr', meaning "reunion of broken parts".


x is often used as the unknown in an algebraic equation, but any letter or symbol will do.

Choose a meaningful letter if possible. For example, t for time, h for height, or r for radius - depending on what quantity you are trying to find.


The famous scientist Albert Einstein learned algebra from a young age.

His Uncle Jakob gave him books on the subject and called algebra "a merry science".

He compared algebra to hunting a little animal. You didn't know the name of the animal, so you called it "x". When you finally caught the animal you gave it the correct name.