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What is it?

The binary number system is a base-2 number system. This means it only has two numbers: 0 and 1. All information in a computer (words, pictures, movies, sound) is stored and transmitted as sequences of bits, or binary digits. A bit is a single piece of data which can be thought of as either zero or one. Each binary number is made up of bits, for example, the number 1010 is made of 4 bits. When you have 8 bits altogether, this is known as a byte. A byte may look like the number 01000100 and in this case represents the letter ‘D’.

Australian Curriculum definition


A use of two states or permissible values to represent data, such as ON and OFF positions of a light switch or transistors in a computer silicon chip that can be in either the electrical state of ON or OFF. Binary data are typically represented as a series of single digits referred to as binary digits (or bits) due to each taking on the value of either 0 or 1. The image below shows how a dashed line might be represented in binary.


Source: Australian Curriculum: Technologies glossary 

Lesson Ideas

How to teach it





Binary work samples

Students were introduced to whole numbers using a CS Unplugged video and unplugged group activities. Students completed a worksheet to assess their understanding of binary numbers.

Case studies

What other schools are doing

Good News Lutheran School

Bits of Binary

Teachers at Good News Lutheran School are exploring ways to teach the content and skills of the new Digital Technologies Curriculum. The Year 5 teachers collaborated with the Digital Learning Facilitator to present a sequence of lessons introducing the concept of binary numbers through online and unplugged activities.

Curriculum links

Level F–2:

Recognise and explore patterns in data and represent data as pictures, symbols and diagrams (ACTDIK002)

Levels 3–4

Recognise different types of data and explore how the same data can be represented in different ways (ACTDIK008)

Levels 5–6

Examine how whole numbers are used to represent all data in digital systems (ACTDIK015)

Levels 7–8

Investigate how digital systems represent text, image and audio data in binary (ACTDIK024)

Levels 9–10

Analyse simple compression of data and how content data are separated from presentation (ACTDIK035)