# Binary numbers

Computers today use digits to represent information - that's why they're called digital systems. The simplest and most common way to represent digits is the binary number system, with just two digits (usually written as 0 and 1). It is called binary because there are only two different digits used, or two states. This unit and lessons explore how the binary system works and why it’s important to understand how data is represented.

Computers today use digits to represent information - that's why they're called digital systems. The simplest and most common way to represent digits is the binary number system, with just two digits (usually written as 0 and 1). It is called binary because there are only two different digits used, or two states.

See teaching this in action

A bit is usually stored in a memory cell inside a computer, which is an electronic circuit that can be set to a high voltage level (1) or a low voltage level (0); on disks they are represented by magnetism or optical reflection.

There are billions of these bits on a typical computer, and they are used to store text, numbers, images, video, and anything else that we need to store or transmit. On computer networks the bits are communicated by light, voltages or sound. Anything that can have two different values …

## Lessons

Ages 5 to 7 Programming challenges
In the teacher observations sections there may also be background notes on the big picture. There is no expectation that 5 to 7 year olds will need to know this, but if you are asked, you have the answer at your fingertips.
1 How binary digits work No
2 Reinforcing sequencing in binary number systems No
3 Codes for letters using binary representation No
Ages 8 to 10 Programming challenges
1 How binary digits work Yes
2 Reinforcing sequencing in binary number systems No
3 Codes for letters using binary representation No

## Curriculum Integrations

Activity Curriculum Areas Prerequisite Lessons?
Binary Candles or Normal Candles on your Cake Literacy: Writing Yes
Whose cake is it? Literacy: Writing Yes
Binary Name Necklaces Art Yes
Binary Patterns Art Yes
Binary Tunes Performing Arts: Music Yes
Biographies and binary number system history Literacy: Reading Literacy: Writing No
Binary Art Art Yes