Data Compression
Summary
Materials
Instructional Activities and Classroom Assessments
- Data Compression Introduction (10 minutes)
- Lossless and Lossy in Images (20 minutes)
- Debrief (5 minutes)
- Text Compression (10 minutes)
- Extension Activity
Learning Objectives
- DAT-1.D Compare data compression algorithms to determine which is best in a particular context.
Essential Knowledge
- DAT-1.D.1 Data compression can reduce the size (number of bits) of transmitted or stored data.
- DAT-1.D.2 Fewer bits does not necessarily mean less information.
- DAT-1.D.3 The amount of size reduction from compression depends on both the amount of redundancy in the original data representation and the compression algorithm applied.
- DAT-1.D.4 Lossless data compression algorithms can usually reduce the number of bits stored or transmitted while guaranteeing complete reconstruction of the original data.
- DAT-1.D.5 Lossy data compression algorithms can significantly reduce the number of bits stored or transmitted but only allow reconstruction of an approximation of the original data.
- DAT-1.D.6 Lossy data compression algorithms can usually reduce the number of bits stored or transmitted more than lossless compression algorithms.
- DAT-1.D.7 In situations where quality or ability to reconstruct the original is maximally important, lossless compression algorithms are typically chosen.
- DAT-1.D.8 In situations where minimizing data size or transmission time is maximally important, lossy compression algorithms are typically chosen.
Details
1. Data Compression introduction (10 minutes)
- Explain what data compression is.
- Explain why we need data compression.
- Discuss the cost of data storage.
- Discuss the two types of data compression.
2. Lossless and Lossy in Images (20 minutes)
- Discuss lossy and lossless in images.
- Create an image activity.
3. Debrief (5 minutes)
- Discuss students observations regarding the different image files they created.
4. Text Compression (10 minutes)
- Discuss how text compression programs work.
- Discuss Run Length Encoding.
5. Extension activity
- If you finish early, students can read Reduce the file size of your Word documents - Word.