Ch. 1
Ch. 2

# Optional Lesson: Sending Bits in the Real World

## Overview

In this lesson, students will be introduced to how bits are transmitted over the most common mediums (copper wire, fiber-optic cable, and radio waves) used to connect devices on the Internet. They then chose a device that transmits bits and research that device and the system it uses. Students create a poster presenting their findings, and the lesson concludes with a gallery walk of the posters.

## Purpose

Binary information must be encoded in some way before transmission over the Internet. There are a few methods for encoding bits that are used far more often than others. Copper wire is used to transmit binary messages using electricity - a voltage on the wire means one state, and no voltage means the other. Fiber-optic cables, on the other hand, use light (on or off) to transmit a binary message. Radio waves can be used to send binary information by altering the frequency or amplitude of the wave. Each method has benefits and drawbacks which make it better suited for some situations than others. Together these different systems form the network of bit-sending devices we know as the Internet. A single bit sent from a cell phone in North America to someone in China probably travels over radio waves, fiber-optic cable, and copper wire while on its journey.

## Objectives

### Students will be able to:

• Identify how household items use these technologies to send, receive, or store information.
• Differentiate between three common methods for transmitting bits across the Internet.

## Preparation

• 8.5 x 11 or poster paper
• materials for creating poster

Heads Up! Please make a copy of any documents you plan to share with students.

## Support

### Report a Bug

Differentiation and accommodations for this lesson

# Teaching Guide

## Getting Started

Goal: This video synthesizes material from the previous three lessons, and introduces more concepts about how information is transmitted over the Internet. Students should come away with the ability to describe how bits are sent through physical media, and list each method’s pros and cons.

### Show video: "The Internet: Wires, Cables & WiFi."

Video: If you wish, ask students to open their journals to take notes on a video describing how binary information is actually sent on the Internet. If you choose, you may use Video Guide for "The Internet: Wires, Cables & WiFi" - Worksheet to help students pick out key information.

### Prompt: What materials are used to send bits on the real Internet?

Discussion: Following the video, ask students to finish taking notes and compare what they wrote with their neighbors. They should write down any information they may have missed by consulting with classmates. Then lead a quick discussion reviewing concepts covered in the video. Once students feel comfortable with the three methods of sending bits and their major distinctions, it’s OK to move on.

Prompts:

• For each medium, how is the information encoded?
• Why are all three methods of sending bits used? Why isn’t there one “best” way of sending bits across the Internet? Provide instances when you’d want to use one method vs. another.

Teaching Tips

It might be necessary to differentiate between some common terms like WiFi and the actual physical way that WiFi works, which is to use radio waves of differing frequencies. If you don’t know how every device transmits information don’t worry, students will have an opportunity to go find out shortly.

## Extended Learning

Other videos that can support the content covered in this section:

• James May addresses the need for/use of protocols in communicating across different devices: http://www.youtube.com/watch?v=C3sr7_0FyPA
• Science Scrapbook explores the physical systems/networks, protocols, and routes that information must navigate in order to be transmitted from one device to another: http://www.youtube.com/watch?v=oj7A2YDgIWE
• Andrew Bloom TED talk about the physical Internet and how it works: http://www.youtube.com/watch?v=XE_FPEFpHt4
• Blown to Bits (www.bitsbook.com), Chapter 8, Bits in the Air, pp. 260-272 (How Broadcasting Became Regulated) Chapter 8 (some explicit language) | Chapter 8 (clean/edited version) Then answer the following questions:
• What early regulatory body later became the FCC?
• What mediums are now under their oversight?
• Should the FCC regulate additional mediums, such as the variety of electronic mediums that have sprung up in the digital era? Why or why not?

## Assessment

Rubric:

Prompts:

• Match the bit-sending technology with underlying technology.
• Copper wire, fiber-optic cable, radio waves
• Electric voltage, beams of light, alternating frequencies
• Choose a bit sending technology you learned about today (electricity, light, radio waves) and describe the pros and cons of using this technology.
• Describe how a single bit might be transmitted from a laptop in a coffee shop in Chicago, to someone’s phone in China. How is a single bit physically transmitted from one place to another?

## Activity

### Sending Bits in the Real World: Exploring real-world data transmission systems.

Introduction: We’re going to use our new understandings of how bits travel across the Internet to learn more about bit sending devices we use every day. You will choose a familiar digital device that transmits information and research which bit sending technology it uses. Once you’ve completed your research you’ll be asked to create a poster to present your findings to your classmates. You’ll be asked to find:

• The bit-sending technology used by your device (copper wire, fiber-optic, radio waves). Why do you think this technology is used to perform its function as opposed to the others that do the same?
• The average bit rate of the device.
• The approximate year this device was first used and whether it’s still in use today.
• Something interesting you learned while researching. Some ideas include:
• Average price per bit.
• Potential security issues with device.
• How the technology developed over time.

Distribute: The research and presentation Sending Bits in the Real World - Activity Guide as well as Rubric - Sending Bits in the Real World - Rubric. Students should complete the activity guide with the information requested above. They will be presenting a poster (this can be an 8.5 x 11 piece of paper) that should highlight the information described in the activity guide.

Research: Students research a real world bit-encoding device. Some options are: wired internet (e.g. over ethernet), WiFi router, cell phone, cable television, broadcast television, satellite television, fax machine, dial-up Internet, Bluetooth headset, TV remote. Students may also come up with their own device.

Teaching Tips

Try to achieve a good mix of projects in the class by asking that at most three students research the same device.

Students will likely not find the answer to all of these questions at a single source, and they may need to consult many resources. If it seems some information is unavailable they can make a best guess based upon information they were able to find.

Students may find themselves reading a lot of technical documentation during this activity. There is no expectation that they do so, and in fact there may be one or two questions they cannot answer for their device. Reassure students this is OK and ask them to make their best guesses, based on their research. The primary goal is that they gain familiarity with the concepts, not that they find specific statistics.

## Wrap-up

Present: Once all students are done they should post their projects around the room and complete the Gallery Walk Reflection at the bottom of the rubric.

Alternatively consider some other share-out activity; see Teaching Strategies for the CS Classroom - Resource.

• Reflection: starting out in computer science
• 3
• (click tabs to see student view)
View on Code Studio

## Starting out in Computer Science

Computer science has changed the way we communicate with each other, make art and movies, grow food, and even treat illnesses. Everyone can learn computer science and make a difference.

## Quotes from students

Still, we understand that taking a computer science course can be difficult at first. Here are a few student quotes describing their strategies and tips for taking this course. Please read the quotes carefully and respond to the prompt below.

In the first week of this class I was falling behind quickly. There was a lot of new information to learn. To keep up, I had to find a better way to study. I tried to find connections between the material and what I already know. That really helped me remember things. I also tried to not overdo it. I started taking small breaks in-between lessons and when I came back I checked if I still remembered what I was studying before. It helped a lot

Sofia P. (age 16)

Some days I felt tired and would drift away in my thoughts. It was a real problem because I would miss so much of what we were learning. So I started going to bed a bit earlier and I tried my best to pay attention. At the end of every class our teacher summarized what we learned that day and that was really helpful. I started taking more notes because that also kept my mind from wandering. These little tricks got me through the class and I learned more.

Jasmin D. (age 17)

I can be pretty forgetful sometimes and it was a problem in this class. I think it's because we did so much on the computer. For my other classes I take notes on paper and read through them again at home. So the trick that I found helpful in this class was to take notes on paper anyway and to test myself about the concepts. I wasn't sure if it would work at first, but I think it ended up being a big help.

Sam J. (age 17)

Now consider the strategies and insights for how to learn best that you just read.

## Reflect and Summarize:

What are your own strategies and insights about how to learn best? And, how are they similar or different to the ones that you just heard about from other students?

Please write a short paragraph. Don't worry about spelling, grammar, or how well written it is.

## Standards Alignment

#### CSTA K-12 Computer Science Standards (2011)

CD - Computers & Communication Devices
• CD.L2:6 - Describe the major components and functions of computer systems and networks.
• CD.L3A:9 - Describe how the Internet facilitates global communication.
CI - Community, Global, and Ethical Impacts
• CI.L3B:2 - Analyze the beneficial and harmful effects of computing innovations.
• CI.L3B:4 - Summarize how computation has revolutionized the way people build real and virtual organizations and infrastructures.

#### Computer Science Principles

2.1 - A variety of abstractions built upon binary sequences can be used to represent all digital data.
2.1.1 - Describe the variety of abstractions used to represent data. [P3]
• 2.1.1A - Digital data is represented by abstractions at different levels.
• 2.1.1B - At the lowest level, all digital data are represented by bits.
• 2.1.1C - At a higher level, bits are grouped to represent abstractions, including but not limited to numbers, characters, and color.
• 2.1.1E - At one of the lowest levels of abstraction, digital data is represented in binary (base 2) using only combinations of the digits zero and one.
2.1.2 - Explain how binary sequences are used to represent digital data. [P5]
• 2.1.2D - The interpretation of a binary sequence depends on how it is used.
• 2.1.2E - A sequence of bits may represent instructions or data.
• 2.1.2F - A sequence of bits may represent different types of data in different contexts.
3.3 - There are trade offs when representing information as digital data.
3.3.1 - Analyze how data representation, storage, security, and transmission of data involve computational manipulation of information. [P4]
• 3.3.1A - Digital data representations involve trade offs related to storage, security, and privacy concerns.
• 3.3.1B - Security concerns engender tradeoffs in storing and transmitting information.
6.1 - The Internet is a network of autonomous systems.
6.1.1 - Explain the abstractions in the Internet and how the Internet functions. [P3]
• 6.1.1A - The Internet connects devices and networks all over the world.
• 6.1.1B - An end to end architecture facilitates connecting new devices and networks on the Internet.
• 6.1.1C - Devices and networks that make up the Internet are connected and communicate using addresses and protocols.
• 6.1.1D - The Internet and the systems built on it facilitate collaboration.
6.2 - Characteristics of the Internet influence the systems built on it.
6.2.1 - Explain characteristics of the Internet and the systems built on it. [P5]
• 6.2.1A - The Internet and the systems built on it are hierarchical and redundant.
• 6.2.1D - Routing on the Internet is fault tolerant and redundant.
6.2.2 - Explain how the characteristics of the Internet influence the systems built on it. [P4]
• 6.2.2A - Hierarchy and redundancy help systems scale.
• 6.2.2B - The redundancy of routing (i.e., more than one way to route data) between two points on the Internet increases the reliability of the Internet and helps it scale to more devices and more people.
• 6.2.2C - Hierarchy in the DNS helps that system scale.
• 6.2.2D - Interfaces and protocols enable widespread use of the Internet.
• 6.2.2E - Open standards fuel the growth of the Internet.
• 6.2.2F - The Internet is a packet-switched system through which digital data is sent by breaking the data into blocks of bits called packets, which contain both the data being transmitted and control information for routing the data.
• 6.2.2G - Standards for packets and routing include transmission control protocol/Internet protocol (TCP/IP).
• 6.2.2H - Standards for sharing information and communicating between browsers and servers on the Web include HTTP and secure sockets layer/transport layer security (SSL/TLS).
• 6.2.2I - The size and speed of systems affect their use.
• 6.2.2J - The bandwidth of a system is a measure of bit rate â€” the amount of data (measured in bits) that can be sent in a fixed amount of time.
• 6.2.2K - The latency of a system is the time elapsed between the transmission and the receipt of a request.