Chapter 6.2 - Computer Networking
Time Estimate: 45 minutes
6.2.1. Introduction and Goals
Computer systems and networks is one of the five Big Ideas of the CS Principles (CSP) curriculum and rightly so: The Internet has had a tremendous impact on our lives and on modern society. Yet, despite its impact and influence, most people do not really understand what the Internet is and how it works.
We introduced the Internet in Unit 2, where we covered the following points.
The Internet is the global public network of independent and autonomous networks that are governed by the Internet Protocol Suite.
The Internet is not the same as the World Wide Web (WWW). The WWW is an application that runs on the Internet using HTTP.
The Internet is based on open (non-proprietary) standards, which has enabled it to grow exponentially since its inception in the early 1980s.
The cloud is an everyday term for the Internet and/or WWW.
This lesson provides a high-level overview of some of the Internet's and WWW's key concepts and terminology. A follow-up lesson will go into greater detail in explaining how the Internet works.
Learning Objectives: I will learn to
explain the fundamentals of how the Internet works
describe the client/server model of networking
explain how bandwidth and latency independently affect an internet connection
describe issues that contribute to the digital divide
Language Objectives: I will be able to
use target vocabulary, such as protocol, bandwidth, latency, and digital divide while describing computer networks and their effects on society, with the support of concept definitions and vocabulary notes from this lesson
6.2.2. Learning Activities
Part 1. Basic Concepts and Terminology
In Unit 2 we defined the Internet as a network of disparate networks that is governed by systems of rules, known as protocols. In this first presentation we'll see some examples of different types of networks and we'll learn about the role that special devices known as routers play in enabling communication between different types of networks.
Activity: 6.2.2.1 YouTube (42F4dByfRtY)
Activity 1
Answer the following questions in pairs, groups, or as class discussion:
Which country has the fastest download speeds on the Internet? Is the U.S. in the top 3? Try to guess the answers to these before looking them up on Speed Test Global Stats.
What is the percentage of Internet user penetration for the United States? The Internet user penetration is the percentage of the population that has access to and uses the Internet. Access to the Internet depends on the ability to connect a computing device to an Internet-connected device like a router. Do you think we are close to 100%? Try to guess before you look online. You may get different data depending on the date of the data. Some sources are https://en.wikipedia.org/wiki/List_of_countries_by_number_of_Internet_users and Internet Live Stats site which presents Internet penetration data by country.
Do all countries have similar Internet user penetration or is there a digital divide (a gap between those who have Internet access and those who don't)? How big is the digital divide between continents or countries? Find data online using the sources above or others to answer this question.
What can we do to reduce the effects of the digital divide both locally and globallly? Discuss in your class.
The digital divide refers to a gap or differing access to computing devices and the Internet based on socioeconomic, geographic, or demographic characteristics. It can affect both groups and individuals and can be affected by individuals, organizations and government actions. The digital divide raises issues of equity, access, and influence, both globally and locally. The digital divide is huge when we compare first and third world countries. But even students in the U.S. experience the digital divide in different schools. If you're interested in this topic, watch the National Geographic's Without a Net: Digital Divide documentary.
Part 2. Client/Server Model
When you are using the Internet to read email or visit a web site, your device (phone or tablet or computer) is playing the role of a client. It is using client software, such as a web browser or email application to communicate with a server, which is computer on the Internet that provides a specific service, such as email or web browsing. Clients and servers form a computing system which is a group of computing devices and programs working together for a common purpose. The TCP and IP protocols route messages between the clients and servers finding a path from the sender to the receiver. In this next presentation we'll look at how communication occurs between a client and server using HTTP.
Activity: 6.2.2.2 YouTube (DDGnPTpk_G8)
Activity 2: Client/Server Model
Complete the activity in this worksheet to review the client/server model.
Part 3. Internet Performance
In this next presentation we learn about two important measures of Internet performance. The first, bandwidth, refers to the amount of data that can be sent in a fixed amount of time and is usually measured in kilobits or megabits per second. The second, latency, refers to how long it takes a packet of data to go from its source (e.g., a client) to its destination (e.g., a server). You'll be introduced to some easy-to-use tools that will enable you to measure bandwidth and latency from your home or school networks.
Activity: 6.2.2.3 YouTube (pg7oQhR5QX0)
Activity 3: Measuring Bandwidth and Latency
Use the http://www.bandwidthplace.com/ tool (or http://speedtest.xfinity.com/) to measure the bandwidth and latency of your Internet connection.
What are the download and upload speeds for your Internet connection? Note that these bandwidth are measured in megabits per second (Mbps). Why do you think Internet Service Providers (ISPs) provide different bandwidths for downloading and uploading from the Internet?
Measure the bandwidth at school and at home. Are they different? How do they compare to the fastest download speeds you found in Activity 1 on the Speed Test Global Stats site?
This speed test also provides a latency test using a utility called ping which returns the amount of time (usually measured in milliseconds) to send a small packet of data from one computer (the bandwidthplace server) to another (your computer). What is the latency for your connection? Why is this a useful measurement?
6.2.3. Summary
In this lesson, you learned how to:
Learning Objective CSN-1.A: Explain how computing devices work together in a network.
A computing system is a group of computing devices and programs working together for a common purpose.
A computer network is a group of interconnected computing devices capable of sending or receiving data.
A computer network is a type of a computing system.
The bandwidth of a computer network is the maximum amount of data that can be sent in a fixed amount of time.
Bandwidth is usually measured in bits per second.
Learning Objective CSN-1.B: Explain how the Internet works.
The Internet is a computer network consisting of interconnected networks that use standardized, open (nonproprietary) communication protocols.
Access to the Internet depends on the ability to connect a computing device to an Internet-connected device.
A protocol is an agreed-upon set of rules that specify the behavior of a system.
The protocols used in the Internet are open, which allows users to easily connect additional computing devices to the Internet.
Learning Objective IOC-1.C: Describe issues that contribute to the digital divide.
Internet access varies between socioeconomic, geographic, and demographic characteristics, as well as between countries.
The digital divide refers to differing access to computing devices and the Internet, based on socioeconomic, geographic, or demographic characteristics.
The digital divide can affect both groups and individuals.
The digital divide raises issues of equity, access, and influence, both globally and locally.
The digital divide is affected by the actions of individuals, organizations, and governments.
Learning Objective IOC-1.F: Explain how the use of computing can raise legal and ethical concerns.
The digital divide raises ethical concerns around computing.
6.2.4. Still Curious
This video contains a very visual example of bandwidth using balloons and pipes that you could even recreate in your classroom.
This video compares bandwidth to vehicles such as buses and race cars. It also explains latency concepts in terms of the speed of light and queues (lines).
6.2.5. Self-Check
Here is a table of some of the technical terms we've introduced in this lesson. Hover over the terms to review the definitions.
network
World Wide Web
client
server
computing system
protocol
SMTP/POP
URI
digital divide
ethernet
host
bandwidth
latency
modem
LAN
WAN
HTTP
HTML
router
routing
Internet Service Provider (ISP)
wifi
Q-4: True or False: Cloud computing is made possible by the Internet and the World Wide Web and employs a computation model known as client-server computing.
A. True
B. False
Q-5: A phone is an example of a __________.
A. b. server
B. a. client
Q-6: Google’s search engine is an example of a __________.
A. a. client
B. b. server
Q-7: Bandwidth measures ___________________.
A. the average length of e-mails that you can send on a daily basis
B. how fast your computer can connect to the Internet
C. the amount of data that can be sent in a fixed amount of time
D. the amount of time it takes to send data over the Internet
Q-8: Latency measures ___________________.
A. the average number of messages you send over the Internet in a day
B. the size of the messages that you send over the Internet
C. how much data can you send in a specific amount of time.
D. the amount of time it takes to send a message over the Internet
Q-9: AP 2021 Sample Question: Which of the following school policies is most likely to have a positive impact on the digital divide?
A. A school allows students to bring a tablet computer to class every day to participate in graded quizzes.
B. A school provides a laptop or tablet computer to all students enrolled at the school.
C. A school allows students to bring a graphing calculator from home to complete in-class mathematics assignments.
D. A school recommends that all students purchase a computer with as much processing speed as possible so that projects run faster.
6.2.6. Reflection: For Your Portfolio
Answer the following portfolio reflection questions as directed by your instructor. Questions are also available in this Google Doc where you may use File/Make a Copy to make your own editable copy.
Complete the following table, using your own words to define each term.
Term
Your Definition
Units used to measure it
Why is it a useful measure?
bandwidth
latency
What do you think affects the differences in bandwidth globally as well as in different locations in the U.S.?
What is the digital divide? What are some ways to reduce the effects of the digital divide?
(Activity 2) Include a screenshot or photo of your finished diagram.
Portfolio Reflection Questions
Make a copy of this document in your Portfolio Assignments folder and answer these questions in the spaces below. Once complete, turn in this assignment according to the steps given by your teacher.
6.2 Computer Networking Curriculum Page
Answer the following questions:
1. Complete the following table, using your own words to define each term.
Term
Your Definition
Units used to measure it
Why is it a useful measure?
bandwidth
latency
2. What do you think affects the differences in bandwidth globally as well as in different locations in the U.S.?
Answer
3. What is the digital divide? What are some ways to reduce the effects of the digital divide?
Answer
4. (Activity 2) Include a screenshot or photo of your finished diagram.
Answer
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