Section 2.8

Learning Goals

• CSN-1.B: Students will explain how the Internet works.

• Students will evaluate the impact of open protocols on the scalability of the Internet.

• Students will identify and describe commonly used protocols used in the Open Systems Interconnection (OSI) model.

• CSN-1.B.1: The Internet is a computer network consisting of interconnected networks that use standardized, open (nonproprietary) communication protocols.

• CSN-1.B.2: Access to the Internet depends on the ability to connect a computing device to an Internet-connected device.

• CSN-1.B.3: A protocol is an agreed-upon set of rules that specify the behavior of a system.

• CSN-1.B.4: The protocols used in the Internet are open, which allows users to easily connect additional computing devices to the Internet.

• CSN-1.B.5: Routing on the Internet is usually dynamic; it is not specified in advance.

• CSN-1.B.6: The scalability of a system is the capacity for the system to change in size and scale to meet new demands.

• CSN-1.B.7: The Internet was designed to be scalable. 

Important Vocabulary:  HTTP, HTTPS, HTML,  IP,  UDP , TCP, IP, SSL/TLS, protocol, scalability, hierarchical, OSI model

Objectives and General Description

From the APCSP course description:    The Internet is a computer network consisting of interconnected networks that use standardized, open (nonproprietary) communication protocols. 

One widely used conceptual framework to explain the interconnections in the internet is the OSI model.    The objective of this section is to introduce students to the OSI model and have students investigate common open protocols at each layer of the OSI model.  Students will also explain how open protocols have helped facilitate the scalability of the Internet.

The lesson begins with a video about HTML & HTTP.  Students will have guided notes.  This video can be completed in a flipped format with students coming to class already having watched it and ready to discuss.  During this discussion the teacher will also review the packet switching activity from Section 2.7 and will highlight the key concepts.  Students will work with a partner to research the OSI model, find & describe common protocols at each layer and create an artifact that is evidence of learning this material.  Students are given choices in how they show mastery of these concepts.

Activities

Activity 2.8.1 Video introduction (Assign as out of class)

1. The video and guided notes can be completed prior to class (flipped model).

2. Students will watch The Internet:  HTTP & HTML.  The video is 7 minutes long.

3. Students complete the HTTP & HTML Video Guided Notes.

4. Class discussion on important video content.

Activity 2.8.2 (Budget 55 minutes)

1. Emphasize that students have learned about the protocols involved in packet switching and addressing.  Have students quickly list the protocols that they have learned. Introduce the concept of multiple layers of protocols to move data across the internet.  One example of this is the OSI model.  There are 7 layers, each of which has associated protocols.  

2. Students will work with a partner to research and explain the OSI model.  Their product should answer the following questions:

   1. What are the layers and what is the order of layers?

   2. What is the purpose of each layer?

   3. Which are hardware layers?  Software layers?

   4. What are common protocols at each layer?  Be sure to include:  HTTP, SSL/TLS, TCP, IP, SMTP, Telnet, FTP, UDP, HTML, MIME

3. Give students a copy of the OSI assignment  Students should create a digital artifact to convey their knowledge of the OSI model.  Ideas include:  word document with charts, prezi, powerpoint, webpage, video, etc. 

4. Resources for research can include:

   1. https://www.geeksforgeeks.org/layers-osi-model/

   2. https://www.webopedia.com/quick_ref/OSI_Layers.asp

   3. https://www.javatpoint.com/computer-network-tcp-ip-model

   4. https://www.networkworld.com/article/3239677/the-osi-model-explained-how-to-understand-and-remember-the-7-layer-network-model.html

5. Differentiated assignments:

   1. For students who need more scaffolding, provide them with an OSI worksheet to complete.

   2. For students who are more advanced and need a more challenging assignment, challenge them to experiment with HTML and create a webpage in NotePad++.  The content of the page will be the explanation of the OSI model, either in text, graphics or both.

      1. W3 Schools HTML tutorial

      2. NotePad++

Note:  APCSP course standards do not require students to memorize the OSI.  Students need an understanding of the layered nature of the protocols and an understanding that the protocols are part of an open system.  The students should know the functionality of the following protocols (not specific or technical details of how specific versions of the protocols work):  HTTP, TCP/IP, SSL/TLS, UDP, HTML

Activity 2.8.3 (optional assignment)

Read the appendix section “The Internet as System and Spirit” of Blown To Bits and answer these questions.  

Activity 2.8.4 (optional assignment)

Students complete a "Journey thru a Computing System" project.  Students create a digital artifact that describes the journey information takes to go from their own computer to the innovations website and back.

Resources

• 2.8.1: HTTP & HTML Video Guided Notes (student worksheet)

• 2.8.1: HTTP & HTML Video Guided Notes KEY (teacher resource)

• 2.8.2: OSI Assignment (student resource)

• 2.8.2: OSI Worksheet for Differentiated Assignment (student worksheet)

• 2.8.3: The Internet as System and Spirit assignment (student worksheet)

• 2.8.4: Journey thru a Computing System (student resource)