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ACARA Digital Technologies Years 9–10 — Data Compression

Making files smaller, and what you lose when you do.

Modules (40)

1 Why file size matters 2 Storage units: KB, MB, GB, TB 3 Representing text with number codes 4 Representing images with pixels 5 How images are made of numbers 6 Image resolution 7 Colour depth 8 How sound is turned into binary 9 Sample rate and audio quality 10 Sample resolution 11 Compression - losing quality or saving space? 12 Why compression is needed: less storage space 13 Why compression is needed: less bandwidth 14 Why compression is needed: shorter transmission time 15 Redundancy: repeated data that can be shortened 16 Lossless compression 17 Dictionary (substitution) compression 18 Shorter codes for frequent characters 19 Run-length encoding: encoding text 20 Run-length encoding: decoding 21 Run-length encoding of a row of coloured pixels 22 Run-length encoding of a pixel image 23 Decoding run-length encoded image data 24 When run-length encoding makes data bigger 25 Decompressing a file 26 Lossy compression 27 Lossy compression permanently removes data 28 Effect of resolution and colour depth on image quality and file size 29 Lossy compression of an image by reducing resolution or colour depth 30 Effect of sample rate and resolution on accuracy and file size 31 Lossy compression of a sound by reducing sample rate or sample resolution 32 Audio bitrate (kbps) 33 Exporting audio at different quality levels in Audacity 34 How video compression reuses unchanged parts of frames 35 Streaming media and adjusting bitrate 36 Comparing lossy and lossless compression 37 Common compressed file formats and what they are used for 38 Calculating compression ratio and space saved 39 Choosing a compression format for a task 40 Explaining what is lost and what is kept when a file is compressed

Printables for this journey

Every module above has its own free printable worksheet with an answer key. These crosswords and word searches cover the same terms:

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Issues in Technology Crossword: Is AI using too much power? and more (Part 1 of 2) 10 clues · Is AI using too much power?, How does an AI actually work?, Compression - losing quality or saving space?, Why file size matters and more
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Issues in Technology Word Search: Is AI using too much power? to What is RADCAB? (All modules) 22 words to find · Is AI using too much power?, How does an AI actually work?, Compression - losing quality or saving space?, Why file size matters and more
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Years 5–6 Data & Information Crossword: Data, information and binary representation (Modules 1–10) 10 clues · Data and information, Types of data: numbers and text, Types of data: images, sound and video, Same data, different representations and more
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Years 5–6 Data & Information Crossword: Data, information and binary representation and Acquiring and manipulating data (Modules 11–20) 10 clues · Representing images with pixels, Primary and secondary data sources, Collecting data with a survey, Spreadsheet rows, columns and cells and more
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Years 5–6 Data & Information Word Search: Data, information and binary representation and Acquiring and manipulating data (Modules 1–20) 20 words to find · Data and information, Types of data: numbers and text, Types of data: images, sound and video, Same data, different representations and more
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Years 7–8 Digital Systems Crossword: Hardware for particular tasks (Modules 4–19) 10 clues · CPU clock speed (GHz), CPU cores, HDD vs SSD performance, Storage units: KB, MB, GB, TB and more
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Years 7–8 Digital Systems Word Search: Hardware for particular tasks to Account security and cyber threats (Modules 4–74) 20 words to find · CPU clock speed (GHz), CPU cores, HDD vs SSD performance, Storage units: KB, MB, GB, TB and more
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Years 7–8 Data & Information Crossword: Representing data with binary and Acquiring, storing and validating data (Modules 9–45) 10 clues · 8-bit binary numbers and the range 0 to 255, Converting a larger decimal number to binary, How many values n bits can store, Looking up characters in the ASCII table and more
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Years 7–8 Data & Information Word Search: Representing data with binary to Using digital tools and conventions (Modules 9–80) 22 words to find · 8-bit binary numbers and the range 0 to 255, Converting a larger decimal number to binary, How many values n bits can store, Looking up characters in the ASCII table and more
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Years 9–10 Data & Information Crossword: Data compression (Modules 6–16) 10 clues · Redundancy: repeated data that can be shortened, Lossless compression, Lossy compression, Run-length encoding: encoding text and more
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Years 9–10 Data & Information Crossword: Data compression to Acquiring, storing and validating data (Modules 17–51) 10 clues · Choosing a compression format for a task, Content, structure and presentation of a document, Restyling one document with a different stylesheet, Why separating content, structure and presentation matters and more
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Years 9–10 Data & Information Word Search: Data compression to Data privacy and the Australian Privacy Principles (Modules 6–132) 21 words to find · Redundancy: repeated data that can be shortened, Lossless compression, Lossy compression, Run-length encoding: encoding text and more
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IGCSE Computer Science Paper 1 Crossword: 1.2 Text, Sound and Images and 1.3 Data Storage and Compression (Modules 43–58) 10 clues · Comparing ASCII and Unicode, Analogue sound waves and digital sound, Sample resolution, Effect of sample rate and resolution on accuracy and file size and more
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IGCSE Computer Science Paper 1 Crossword: 1.3 Data Storage and Compression and 2.1 Data Transmission Types and Methods (Modules 86–109) 10 clues · Why compression is needed: less storage space, Why compression is needed: less bandwidth, Why compression is needed: shorter transmission time, Lossy compression permanently removes data and more
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IGCSE Computer Science Paper 1 Word Search: 1.1 Number Systems to 1.3 Data Storage and Compression (Modules 28–58) 20 words to find · Why two's complement is used, The sign bit worth -128, Range of 8-bit two's complement, Converting 8-bit two's complement to denary and more
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IGCSE Computer Science Paper 1 Word Search: 1.3 Data Storage and Compression and 2.1 Data Transmission Types and Methods (Modules 86–120) 21 words to find · Why compression is needed: less storage space, Why compression is needed: less bandwidth, Why compression is needed: shorter transmission time, Lossy compression permanently removes data and more
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Crossword: Content, Structure and Presentation and Data Compression (Modules 155–225) 10 clues · Revealing the layers with View page source and Inspect, Anatomy of a CSS rule: selector, property and value, The color and background-color properties, The text-align property and more
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Crossword: Data Compression and Acquiring and Validating Data (Modules 226–254) 10 clues · Exporting audio at different quality levels in Audacity, How video compression reuses unchanged parts of frames, Streaming media and adjusting bitrate, Common compressed file formats and what they are used for and more
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Word Search: Networked Systems and Access Control to Data Compression (Modules 116–225) 20 words to find · Reading a permission string like rwxr-x---, Network (hardware) firewall, Firewall rule: allow or deny by port, Firewall rule: allow or deny by IP address and more
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Word Search: Data Compression and Acquiring and Validating Data (Modules 226–329) 20 words to find · Exporting audio at different quality levels in Audacity, How video compression reuses unchanged parts of frames, Streaming media and adjusting bitrate, Common compressed file formats and what they are used for and more

Frequently Asked Questions

Are these worksheets free?

Yes — every worksheet and its answer key is free to view, download, and print, with no account required to access any individual module.

Do I need an account?

No account is needed to view or print a worksheet. A free teacher account adds extras like assigning modules to a class and tracking progress automatically — it takes under three minutes to set up and doesn't need a credit card.

What year level is this for?

This curriculum is aligned to the Australian Curriculum (ACARA) and Victorian Curriculum, spanning roughly Years 3 to 10 — from first sequencing and variables through to object-oriented programming and advanced data structures. Start wherever matches your class's current level; each module builds on the last.

Can I print them?

Yes — every module has a one-click Print Worksheet button that generates a printable page with the practice questions and a full answer key.

Is this aligned to a curriculum?

Yes — the module sequence is mapped to the Australian Curriculum (ACARA) and Victorian Curriculum, and a class's progress is reported back against those curriculum bands (e.g. ACARA Years 5–6 sequencing and iteration, Years 7–8 functions and data structures), not just a generic difficulty scale.

Can students use this without a teacher?

Yes — students can start any module and practice directly, no class or account required. Joining a teacher's class with a class code adds progress tracking, class badges, and live Sprints, but isn't needed to work through the worksheets or modules solo.

Do I need to know ACARA Digital Technologies Years 9–10 myself to teach this?

No — every module comes with a full worked answer key, and Cloodit tracks who's stuck automatically, so you don't need to solve each exercise yourself before assigning it or be able to debug a student's work line by line.

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