Lesson Plan

• Describe why reducing file sizes is important for storage and transmission.
• Explain the difference between lossless and lossy compression and when each is appropriate.
• Apply methods such as changing file format, adjusting resolution, colour depth, and using compression tools to reduce file size.
• Calculate percentage reductions and estimate transmission‑time savings.
• Evaluate acceptable quality levels for different media contexts.

• Computer with internet access
• Projector or interactive whiteboard
• Sample high‑resolution image files
• Compression software (e.g., 7‑Zip, WinZip)
• Worksheet with calculation tasks
• Whiteboard and markers

Begin with a quick poll: how many have struggled to send a large photo or video? Explain that limited storage and bandwidth make file‑size reduction essential. Today’s success criteria are to identify reasons for compression, choose appropriate methods, and calculate size savings.

1. Do‑Now (5') – Estimate transmission time for a 5 MB video over a 1 Mbps link; discuss answers.
2. Mini‑lecture (10') – Key concepts: file‑size units, lossless vs lossy compression, common formats.
3. Demonstration (10') – Change an image’s format and resolution; show size differences.
4. Guided practice (15') – Use 7‑Zip to compress a folder; record original and compressed sizes.
5. Hands‑on activity (15') – In pairs, save a high‑resolution photo as JPG at 90 %, 70 % and 50 % quality; calculate percentage reductions and discuss suitable quality for web vs print.
6. Check for understanding (5') – Quick quiz/exit ticket on selecting lossless vs lossy based on file type.

Recap the main strategies for reducing file sizes and their impact on storage and transmission speed. For the exit ticket, each student writes one situation requiring lossless compression and one where lossy is acceptable. Homework: locate a file on their device, apply a compression method, and record the before/after sizes.