Run length encoding
Lesson details
Learning outcome
I can describe and use run length encoding to compress data.
Key learning points
- Run length encoding is a lossless data compression technique that reduces the size of repeating sequences of data.
- Run length encoding uses the concept of redundancy to reduce file size.
- Redundancy is about the repetitive information within a data set, which can be removed without losing essential meaning.
- Run length encoding may not always reduce file size and may not be suitable for all applications.
Keywords
Run length encoding - a common type of lossless compression
Data pattern - a recurring trend, relationship, or structure found within a set of data
Redundancy - repeated or extra data that isn’t needed
Common misconception
Run length encoding always reduces file size.
Run length encoding only works well when data has long repeated patterns. If data is random or has frequent changes, RLE may not reduce the file size and can even make it bigger. For example, compressing "HELLO" with RLE results in "1H1E2L1O".
Teacher tip
Make links to real use cases and explain where run length encoding is commonly used for example bitmap images, printers and document scanning. This will give context to learners and show it's not just theory.
Licence
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.What is the compression ratio?
Q2.What happens when the compression ratio is higher?
Q3.What is the term for the file size before compression?
Q4.What is the term for the file size after compression?
Q5.What does a higher compression ratio require?
Q6.What must be considered when selecting a compression algorithm?
Assessment exit quiz
6 Questions
Q1.What type of compression is run length encoding?
Q2.What does run length encoding use to reduce file size?
Q3.What is redundancy in a data set?
Q4.When does run length encoding work best?
Q5.Which of the following is an example of run length encoding?
Q6.Does run length encoding always reduce file size?
To help you plan your 10 computer science lesson on: Run length encoding, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 computer science lesson on: Run length encoding, 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.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 computer science lessons from the Data compression unit, dive into the full secondary computer science curriculum, or learn more about lesson planning.