AP CSP Day 7 - Lossy Data Compression
AP CSP Day 7 - Lossy Data Compression
Course Information
- Course: AP Computer Science Principles
- Unit: Big Idea 3 - Data & Information (DAT)
- Lesson: Day 7 (50 minutes)
- Learning Objective: DAT-1.C - Explain compression techniques
Learning Objectives
Primary Goals
Students will be able to:
- Explain lossy data compression
- Identify common lossy compression algorithms
- Apply compression techniques to multimedia data
- Analyze the trade-offs of lossy compression on data quality and storage
AP Exam Alignment
- Big Idea 3: Data & Information (27-36% of AP Exam)
- Essential Knowledge: DAT-1.C.1, DAT-1.C.2, DAT-1.C.3
- Computational Thinking Practice: 2.D - Compress data using algorithms
Lesson Structure (50 minutes)
Opening Hook (10 minutes)
7.1 Welcome & Lesson Preview (5 minutes)
Teacher Activities:
- Welcome students to Day 7
- Review previous lesson's key concepts
- Introduce today's focus on lossy data compression
Student Activities:
- Review previous lesson's materials
- Think about: "What is lossy data compression?"
7.2 Quick Compression Challenge (5 minutes)
Activity: "Compress an Image"
Instructions:
- Groups of 4-6 students
- Compress a given image using lossy techniques
- Discuss the process
Purpose: Activate thinking about lossy compression
Core Content Instruction (20 minutes)
8.1 What is Lossy Data Compression? (10 minutes)
Definition (DAT-1.C.1):
Lossy data compression reduces file size by removing some information.
Key Concepts:
- **JPEG: Common image compression format
- **MP3: Common audio compression format
- **Quality vs. size: Trade-offs in compression
Case Study: The compression of images in a mobile app
- Compression process: Using JPEG for images
- Outcome: A smaller file size with acceptable quality loss
8.2 Common Compression Algorithms (5 minutes)
Algorithms:
- **JPEG: Efficient image compression
- **MP3: Efficient audio compression
- **Quality reduction: Acceptable trade-offs
Examples:
- Mobile app: Image compression using JPEG
- Music player: Audio compression using MP3
8.3 Importance of Lossy Compression (5 minutes)
Why is it important?:
- Storage: Smaller file sizes
- Transmission: Faster data transfer
- Quality trade-off: Acceptable losses for efficiency
Discussion Questions:
- How does JPEG compression work?
- What are the benefits of MP3 compression?
- Why is lossy compression important for efficient storage?
Hands-On Activity (15 minutes)
9.1 Group Project: Lossy Compression Practice (15 minutes)
Activity: "Compress and Evaluate Multimedia Data"
Instructions:
- Groups of 3-4 students
- Compress and evaluate datasets using lossy techniques
- Discuss the process and its applications
- Present findings
Materials:
- **List of datasets to compress
- **Compression worksheet
- **Access to coding environment
Learning Goals:
- **Understand lossy compression
- **Identify compression algorithms
- **Apply compression techniques
- **Present ideas effectively
Assessment:
- **Group participation
- **Compression accuracy
- **Use of compression tools
- **Presentation clarity
Closure & Preview (5 minutes)
10.1 Key Concepts Review (2 minutes)
Today's Learning Highlights:
- ✅ Understanding lossy data compression
- ✅ Identifying compression algorithms
- ✅ Applying compression techniques
- ✅ Analyzing compression trade-offs
AP Exam Connection:
- These concepts will appear in AP exam multiple choice questions
- Understanding compression is crucial for the Explore Performance Task
10.2 Next Class Preview (3 minutes)
Day 8 Topic: "Extracting Information from Data"
- Learning Objective: DAT-1.D - Extract information from data
- Activity: Practicing data extraction techniques
- Homework: Think about a recent program you used. What compression techniques did it use? What could be improved?