Computers and binary
Unit Computers and binary
Year level: 7-8 Topic: Data representations Time: 9 hours
All computer data including text, images and sound is represented using binary. Work between ASCII and Unicode to understand the relationship between them. Encode images using binary. Explore converting between text and sound and the file formats used to store files. Create a website for a user that requires audio support.
Flow of Activities
Binary system
Provide students opportunities to code and encode messages using ASCII, Unicode and Hexadecimal.Bitmap images
Provide online tools that enable students to explore creating images by changing pixels based on a combination of binary digits.Encoding audio
Investigate audio file formats and converting and saving audio files suing relevant software.Accessible webpage
Create a webpage that incorporates images, texts and audio support for text.Activity Binary system
How does a computer encode text?
Australian Curriculum Alignment
- Representation of data (ACTDIK024)
What's this about?
All computer data is represented using binary notation - a number system that uses 0s and 1s. Binary digits can be grouped together into bytes.
All software, music, documents, and any other information that is processed by a computer is stored using binary.
Two standard character sets that students should become familiar with are ASCII and Unicode. In each standard a certain sequence of bits (1s and 0s) stands for a letter or other character.
ASCII is only used for the English language. Unicode uses between 8 and 32 bits per character, so it can represent characters from languages from all around the world.
Hexadecimal is way to write binary numbers more easily. An 8-bit binary number can be written using only two different hex digits.
Learning tasks
- All number systems rely on positional notation. To understand binary numbers first be familiar with the positional notation we use every day with decimal notation.
- Provide students opportunities to code and encode messages using ASCII, Unicode and Hexadecimal. Simple conversions can be done between each.
- Students could present to the class ‘Why Unicode was developed’.
Explore implementing a digital solution that demonstrates how to control appliances, and to investigate home automation. Examples may include programming a binary switch using (0 and 1) as input for off and on, or detecting speech and recognising a command to turn the appliance on or off.
Supporting Resources















Lesson Ideas


Assessment
Explain how text, image and audio data can be represented, secured and presented in digital systems.
Suggested approaches may include
- Presentation or demonstration
- Worksheets and quizzes that demonstrate the ability to convert binary to decimal, decimal to binary.
- Worksheets and quizzes that demonstrate the ability convert hexadecimal numbers to binary and/or decimal formats.
Assessment Resources


Activity Bitmap images
How are images encoded?
Australian Curriculum Alignment
- Representation of data (ACTDIK024)
What's this about?
All computer data is represented using binary notation - a number system that uses 0s and 1s. Binary digits can be grouped together into bytes.
Images onscreen are made up of picture elements (pixels). Bitmap images are organised as a grid of pixels. Each pixel is stored as a binary number and represents a specific colour.
The colour depth is measured in bits. 1 bit per pixel allows for two values (1) white or (0) black. 3 bits per pixel results in 8 available colours in combinations of RGB (000, 001, 011, 100, 101, 111, 110, 111). 8 Bit colour allows for 256 colours.
Commonly images are made up of colours that are a combination of 24 bits. For example, green can be represented in binary as 000000001111111100000000 or in RGB as (0, 255, 0) and as hexadecimal #00FF00. 24-bit colour makes 16,777,216 (256 x 256 x 256) possible colours.
Learning tasks
- Provide online tools that enable students to explore creating images by changing pixels based on a combination of binary digits.
- Introduce hexadecimal as a way to encode pixels.
- Students may explore vector graphics and bitmap graphics and scalability. Explore file formats used to store images.
- Relate the RGB values to other areas where students may be familiar with this use of binary numbers such as when programming an LED on an Arduino board to light up a specific colour or when using Sphero and selecting a particular colour.
Vector and Raster
- There is a difference between these types of graphic images and the file formats used. You may decide to explore this in more detail.
Supporting Resources








Lesson Ideas
Assessment
Explain how text, image and audio data can be represented, secured and presented in digital systems.
Suggested approaches may include
- Artefact Analysis
- Adapted worksheet
- A presentation to explain how RGB values and hexadecimal numbers are used in image manipulation software.
Activity Encoding audio
How does a computer encode audio files?
Australian Curriculum Alignment
- Representation of data (ACTDIK024)
What's this about?
Sounds created on a computer exist as digital information encoded as audio files.
An audio file format is a file format for storing audio. Common audio file formats include MP3, AAC, WMA, FLAC, ALAC, WAV, AIFF, and PCM.
Learning tasks
- Investigate audio file formats, such as MP3, AAC, WMA, FLAC, ALAC, WAV, AIFF, and PCM. How do they differ? Make a list of audio files that students use on their devices. Do this as a group activity and share findings as a class.
- Use audio recording software such as RecordPAd or Audacity to record an audio soundtrack.
- There are several tools that convert between different formats. Use Audacity or similar software to save audio projects in different file formats.
- Explore and analyse the quality of text to speech for example:
- audio books
- a Smartphone that enables spoken messages to send as an SMS.
- A software assistant that uses voice queries to perform actions on a smartphone eg SIRI.
- This activity links with programming. App Inventor or App Lab are free, cloud-based services that enable users to build apps in the web browser. Create an App that uses the functionality of Text to Speech. Consider what prompts the user to speak and what code blocks/code translate.
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Explore implementing a digital solution that demonstrates how to control appliances, and to investigate home automation. Examples may include programming a binary switch using (0 and 1) as input for off and on, or detecting speech and recognising a command to turn the appliance on or off. Alternatively students record an audio file and incorporate this into their computer program. |
Supporting Resources










Lesson Ideas
Assessment
Explain how text, image and audio data can be represented, secured and presented in digital systems.
Suggested approaches may include
- Adapted worksheet
- Record audio and save the recording in different formats. Use a tabular display to demonstrate how the different codecs lead to different file sizes.
- Make the Text to Speech app using Appinventor. Demonstrate the completed app
Activity Accessible webpage
How can I design a website that is accessible to users?
Australian Curriculum Alignment
What's this about?
Many computers and mobile devices today have built in text-to-speech software. Some people with disabilities, including people who are blind, use specialized software called screen readers.
Screen readers provide important functionality such as navigating through headings, speaking image alternatives, and identifying internal and external links. They can also highlight the text as it is being read aloud for people to see and hear the content at the same time. Content must be coded properly so that all of the functionality of the text-to-speech software works with the content.
Learning tasks
- Create a website that incorporates images, texts and audio support for text.
- Build empathy as part of the design process to describe needs of different audiences that may require audio support.
- Define the functional and data requirements based on user needs.
- Explore the use of embedded and linked media elements.
Lesson Ideas






Assessment
Explain how text, image and audio data can be represented, secured and presented in digital systems.
Define and decompose problems in terms of functional requirements and constraints.
Suggested approaches may include
- Design plan
- Artefact analysis