File size and compression
Lesson details
Learning outcome
I can explore what compression is and the impact it can have on the size and quality of a file.
Key learning points
- Compression is used to reduce the size of digital files.
- Lossy and lossless compression affects digital files.
- Using compressed files has both benefits and drawbacks for the use and transfer of file.
Keywords
Lossy compression - a method where data is permanently lost during the compression process and must be approximated when the file is decompressed
Lossless compression - a method of compression where no data is permanently lost during the process
Common misconception
Compression always reduces quality or that compressed files are always lower quality than uncompressed files.
Lossless compression retains all original data by finding and storing repeated patterns more efficiently.
Teacher tip
Just as abbreviating common words saves space in writing, compression algorithms find repetitive patterns in data and replaces them with shorter codes. This reduces file size without losing the essential information.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the smallest unit of data in a computer system?
Q2.What is the term for the number of pixels in an image?
Q3.What happens when you increase the resolution of an image?
Q4.What does colour depth refer to?
Q5.What is the effect of using a higher sample resolution for sound files?
Q6.How does the size of a file affect its transfer speed over a network?
Assessment exit quiz
6 Questions
Q1.What type of compression permanently removes data?
Q2.What is the term for compression that retains all original data?
Q3.Match the terms with their definitions.
Q4.Which compression method is typically used for audio and video files to save space?
Q5.How does compression affect file transfer speeds?
Q6.What is a key feature of lossless compression?
To help you plan your 9 computing lesson on: File size and compression, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 9 computing lesson on: File size and compression, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 3 computing lessons from the Data representation: images and sound unit, dive into the full secondary computing curriculum, or learn more about lesson planning.