Day 2: Computing System Layers

Learning Objectives

• CSN-1.C: Explain how computing devices work together in a network.
• CSN-1.D: Describe the differences between the Internet and the World Wide Web.

Essential Questions

• How are computing systems organized into layers of abstraction?
• How do these layers interact with each other?
• How do abstractions hide complexity in computing systems?

Materials Needed

• Presentation slides on computing system layers
• Layer cards for sorting activity
• Worksheet for mapping user actions to system layers
• Diagram templates for abstraction layers
• Exit ticket templates

Vocabulary

• Abstraction
• Layer
• Hardware layer
• Operating system layer
• Application layer
• Interface
• API (Application Programming Interface)
• System call
• Device driver
• Abstraction hierarchy

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review computing system components from previous lesson
   • Connect to today's focus on how these components are organized into layers

2. Warm-up Activity (5 minutes)

   • Present a simple computing task (e.g., saving a document)
   • Ask students to brainstorm everything that happens "behind the scenes"
   • Create a class list of processes that occur at different levels
   • Introduce the concept of abstraction layers

Main Activities (32 minutes)

3. Lecture: Abstraction Layers in Computing Systems (12 minutes)

   • Define abstraction as hiding complexity while providing functionality
   • Explain the main abstraction layers in computing systems:
     • Hardware layer (physical components)
     • Operating system layer (resource management, interfaces)
     • Application layer (user programs and interfaces)
   • Discuss how each layer interacts with layers above and below it:
     • Interfaces between layers
     • APIs and system calls
     • Device drivers connecting OS to hardware
   • Explain the benefits of layered architecture:
     • Separation of concerns
     • Modularity and maintainability
     • Ability to update one layer without changing others
     • Hiding complexity from users and developers

4. Exploration: Hardware, Operating System, and Application Layers (10 minutes)

   • Demonstrate how a user action triggers operations at each layer
   • Example: Printing a document
     • Application layer: User clicks "Print" in word processor
     • Application makes API calls to operating system
     • Operating system processes request and sends to printer driver
     • Driver converts commands to hardware-specific instructions
     • Hardware layer executes physical printing operations
   • Show how each layer abstracts details from the layer above
   • Discuss how layers enable different specialists to work on different parts

5. Activity: Tracing User Actions Through System Layers (10 minutes)

   • Divide students into pairs
   • Assign each pair a common computing task (e.g., saving a file, playing a video)
   • Have students trace the action through each system layer
   • Students should identify:
     • What happens at the application layer
     • What happens at the operating system layer
     • What happens at the hardware layer
     • How information passes between layers
   • Have pairs share their traces with the class

Closing (10 minutes)

6. Discussion: How Abstractions Hide Complexity (5 minutes)

   • Lead a discussion on the benefits of abstraction in computing
   • Ask students to identify abstractions they use in everyday life
   • Discuss how abstractions enable innovation and specialization
   • Address any misconceptions about system layers

7. Exit Ticket: Mapping User Actions to System Layers (5 minutes)

   • Students complete a worksheet mapping user actions to operations at each system layer
   • Include actions like:
     • Taking a photo with a smartphone
     • Sending an email
     • Streaming a video
   • Collect worksheets before students leave

Assessment

• Formative: Quality of layer tracing activity
• Exit Ticket: Accuracy of mapping user actions to system layers

Differentiation

For Advanced Students

• Ask them to include more detailed operations at each layer
• Have them explore how different operating systems implement the same functionality
• Challenge them to explain how virtualization creates additional abstraction layers

For Struggling Students

• Provide a partially completed layer mapping
• Focus on simpler computing tasks
• Use more visual aids and concrete examples

Homework/Extension

• Research and document the layers involved in a complex computing task
• Compare how the same task is handled on different operating systems
• Create an infographic explaining computing system layers to a non-technical audience

Teacher Notes

• Use analogies to help students understand abstraction (e.g., driving a car without understanding the engine)
• Be prepared to address questions about specific operating systems
• Make connections to abstraction concepts from previous units
• Consider using a demonstration of system monitoring tools to show real-time layer interactions
• Emphasize that understanding system layers helps with troubleshooting and development