Lesson Plan

• Describe the difference between lossless and lossy compression.
• Identify appropriate compression methods for different data types.
• Calculate compression ratios from original and compressed file sizes.
• Compare advantages and disadvantages of common lossless and lossy algorithms.
• Explain the impact of compression choice on data quality and storage requirements.

• Projector or interactive whiteboard
• Slide deck summarising compression concepts
• Sample files (text, image, audio) for demonstration
• Worksheet with compression‑ratio calculations
• Laptop with compression software (e.g., WinZip, image editor)
• Handout of algorithm summaries

Start with a quick poll: “Who has saved a photo as a .jpg or zipped a folder recently?” to activate prior experience. Review the idea that compression reduces file size for storage or transmission. Explain that by the end of the lesson students will be able to choose, apply, and evaluate both lossless and lossy methods.

1. Do‑now (5’) – Students list file types they have compressed and why, sharing briefly (checks prior knowledge).
2. Mini‑lecture (10’) – Define compression, contrast lossless vs. lossy, show real‑world examples.
3. Demonstration (12’) – Live demo: zip a text file (lossless) and convert a photo to JPEG (lossy); discuss basic algorithm ideas.
4. Guided practice (15’) – In pairs, calculate compression ratios for provided sample files using the worksheet.
5. Comparison activity (10’) – Groups complete a Venn diagram comparing advantages and disadvantages of the two approaches.
6. Exit ticket (5’) – Write one scenario needing lossless compression and one where lossy is preferred.

Recap the key distinctions between lossless and lossy methods and how to compute compression ratios. Collect exit tickets to gauge understanding and clarify any misconceptions. For homework, ask students to research another compression algorithm (e.g., LZMA or WebP) and prepare a brief description of its use case.