Grade 9 ICT Textbook PDF

INFORMATION TECHNOLOGY Grade 9 STUDENT’S TEXTBOOK Federal Democratic Republic of Ethiopia Ministry of Education Federal Democratic Republic of Ethiopia Ministry of Education Take Good Care of This Textbook This textbook is the property of your school. Take good care not to damage or lose it. Here are 10 ideas to help take care of the book: 1. Cover the book with protective materials, such as plastic ,old newspapers or magazines. 2. Always keep the book in a clean dry place. 3. Be sure your hands are clean when you use the book. 4. Do not write on the cover or inside pages. 5. Use a piece of paper or cardboard as a bookmark. 6. Never tear or cut out any pictures or pages. 7. Repair any torn pages with paste or tape. 8. Pack the book carefully when you place it in your school bag. 9. Handle the book with care when passing it to another person. 10. When using a new book for the first time, lay it on its back. Open only a few pages at a time. 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INFORMATION TECHNOLOGY Grade 9 Student’s Textbook Writers Tesfaye Bayu (PhD) Werkneh Eshete (MSc) Content Editor Wogene Alemayehu (MSc) Instructional Design Editor Jerusalem Yibeltal (PhD) Language Editor Tagesse Daniel (PhD) Illustrator Kibrebeal Getinet (MSc) Book Designer Efrem Yohannes (PhD) FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA HAWASSA UNIVERSITY MINISTRY OF EDUCATION First Published August 202 3 by the Federal Democratic Republic of Ethiopia, Ministry of Education, under the General Education Quality Improvement Program for Equity (GEQIP-E) supported by the World Bank, UK’s Department for International Development/DFID-now merged with the Foreign, Common wealth and Development Office/FCDO, Finland Ministry for Foreign Affairs, the Royal Norwegian Embassy, United Nations Children’s Fund/UNICEF), the Global Partnership for Education (GPE), and Danish Ministry of Foreign Affairs, through a Multi Donor Trust Fund. © 2023 by the Federal Democratic Republic of Ethiopia, Ministry of Education. All rights reserved. The moral rights of the author have been asserted. No part of this textbook reproduced, copied in a retrieval system or transmitted in any form or by any means including electronic, mechanical, magnetic, photocopying, recording or otherwise, without the prior written permission of the Ministry of Education or licensing in accordance with the Federal Democratic Republic of Ethiopia as expressed in the Federal Negarit Gazeta, Proclamation No. 410/2004 - Copyright and Neighboring Rights Protection. The Ministry of Education wishes to thank the many individuals, groups and other bodies involved – directly or indirectly – in publishing this Textbook. Special thanks are due to Hawassa University for their huge contribution in the development of this textbook in collaboration with Addis Ababa University, Bahir Dar University and Jimma University. Copyrighted materials used by permission of their owners. If you are the owner of copyrighted material not cited or improperly cited, please contact the Ministry of Education, Head Office, Arat Kilo, (P.O.Box 1367), Addis Ababa Ethiopia. Printed by: GRAVITY GROUP IND LLC P.O.Box 13TH Industr ial Ar ea, Shar jj ah UNITED ARAB EMIRATES Under Ministry of Education Contract no. MOE/GEQIP-E/LICB/G-01/23 ISBN: 978-99990-0-0 40-6 Table of Contents UNIT 1 : ORGANIZATION OF FILES 1.1 Basics of Files and Folders 1 1.2 Managing Files and Folders 5 1.3 Computer Drives 25 1.4 Unit Summary 29 1.5 Unit Review Exercise 31 UNIT 2 : COMPUTER NETWORK 2.1 Definition of Network 37 2.2 Fundamental Elements of Network 38 2.3 Types of Networks 46 2.4 Advantages and Disadvantages of Network 60 2.5 Unit Summary 63 2.6 Unit Review Exercise 66 UNIT 3 : APPLICATION SOFTWARE 3.1 Using Application Software 72 3.2 Word Processing 72 3.3 Manipulating Data in Spreadsheet 109 3.4 Creating Presentation 121 3.5 Unit Summary 136 3.6 Unit Review Exercise 138 UNIT 4 : IMAGE PROCESSING AND MULTIMEDIA 4.1 Image 145 4.2 Multimedia Production Planning Strategies 147 4.3 Using Image Processing Software 148 4.4 Unit Summary 186 4.5 Unit Review Exercise 187 i UNIT 5 : INFORMATION AND COMPUTER SECURITY 5.1 Definition of Security 192 5.2 Principles of Computer Security 194 5.3 Computer Security Threats 197 5.4 Potential Losses Due to Security Attacks 204 5.5 How to Secure yourself and your Computer Systems 206 5.6 Unit Summary 209 5.7 Unit Review Exercise 211 UNIT 6 : FUNDAMENTALS OF PROGRAMMING 6.1 Defining a Problem and Computational Problem 217 6.2 Steps in Problem Solving 219 6.3 Working with Flowcharts and Block Programming 223 6.4 Problem Solving Approaches 236 6.5 Unit Summary 239 6.6 Unit Review Exercise 240 ii Grade 9 Information Technology Student’s Textbook UNIT 1 ORGANIZATION OF FILES UNIT OUTCOMES At the end of this unit, learners will be able to: Explain file, folder and drive. Manipulate file and folder. Explore drive on computer system. UNIT OVERVIEW This unit introduces you to files and file organization in computer systems. A computer file can be both system generated and created or transferred from other sources in to a computer. You will learn how to manipulate files (creating, copying, renaming, deleting and searching). A file folder is a mechanism to keep your computer files in an organized manner. This unit will deal with folder manipulation mechanisms that operating systems provide. 1.1 Basics of Files and Folders Brainstorming 1. Have you ever visited your family’s “edir” or “ekub” association’s membership information? Do they use paper to keep membership information? 2. What do you think are the limitations of using the above manual filing system (shelf or filing cabinet-based filing system)? Do you think computers are used to store such information? 1 Unit 1 : Organization of Files 1.1.1 Files A file is a collection of data stored in one unit, identified by a filename. It can be a Word, Spreadsheet, PowerPoint Presentation document that you had learnt in Grade 8. Files are represented by an icon in a computer. Thus, icons are small graphical representation of a file. Because there are different file formats, icons are usually used to help identify the type of file or program associated with. In Figure 1.1 below, you can see different types of files on the desktop. Figure 1.1 Common File Icons in Window 10 KEY CONCEPTS ✍ A file stores a data which can be a document, a picture, text, video, audio, etc. ✍ A file has different icons in a computer. 1.1.2 Folders A folder, also called a directory, is a container which is used to store related files together. A folder can also contain another folder inside. A folder contained in another folder is called a subfolder. A good analogy is the manila folders (dossier) seen in an office to store papers or reports. 2 Grade 9 Information Technology Student’s Textbook The difference between a file and a folder is that a file is a collection or group of interrelated data and information whereas a folder is a container used to store different files and subfolders. We can have different types of Files such as text, video, document and image and each has different extensions to identify their types but folders do not have extensions. Figure 1.2 Manila and computer folders Activity 1.1 This activity is designed to help you discuss the importance and advantages of computer folders. Form a group of two to five students in a class and discuss the following questions. 1. Present the way you put things in your home such as your cloths, exercise books and text books. Compare and contrast a messy home and a tidy home. Which one is easy to locate things? 2. In analogous to this, compare and contrast cluttered files shown in Figure 1.3 (a) and organized files in folder shown in Figure 1.3 (b). 3. How do you organize different files such as document, image, video and audio files in your desktop computer? 3 Unit 1 : Organization of Files Figure 1.3 (a) Cluttered file (b) Organized file by folders Importance of Folders Folders help to keep related files organized together as shown in Figure 1.3 b above. This helps to locate files easily. If you had no folders on your computer, your documents, programs and operating system files would all be located in the same place. Folders allow you to have more than one file with the same file name. For instance, you can have a file called My-letter.doc in your My Documents folder and another file called My-letter.doc in a different folder called ’Letter collection’. If all your files were in a single place, every file would need a unique file name. 4 Grade 9 Information Technology Student’s Textbook KEY CONCEPTS ✍ A folder, which is also called a directory, is a container of files. ✍ A folder helps us to organize related files together. 1.2 Managing Files and Folders Brainstorming 1. How are documents created, named/renamed, copied, moved and deleted in paper-based file systems? 2. How is a folder/dossier created, named/renamed, copied, moved and deleted in manual filing system? Do you think there is a way to do such things in computers’ files and folders? In Windows operating system, the primary way of interacting with files and folders is through the File Explorer application. There are also other operating systems, but in this textbook we use Windows operating system. 1.2.1 Using File Explorer A file explorer (which was called Window explorer in applications before Window 10 version) has the following main parts (See Figure 1.4 and Table 1.1). Figure 1.4 File Explorer window 5 Unit 1 : Organization of Files Table 1.1 File Explorer Parts and Their Descriptions Element File Explorer Description and Usage Numbers Elements 1 Navigation Navigation pane allows you to view and access your pane computer’s file and folder structure. On Navigation pane, there is a Quick Access area. It allows you to navigate quickly and easily to the folders that you use regularly or frequently. To add or pin a folder to the Quick access area, right- click on the folder name and then select Pin to Quick access from the drop-down menu. 2 Forward and Enables you to go to folders you have previously Back buttons opened. If you go to a different folder, you can choose the Back button to return to the last folder you accessed. 3 Ribbon Enables you to perform layout, formatting and sharing tasks. It also enables you to change your files’ and folders’ displays. Tasks available to you might differ depending on what folder you select (e.g. Documents versus Pictures). To display the Ribbon, click on one of the menu items at the top of File Explorer or click on Expand the Ribbon button (down-pointing arrow) located at the top right-hand side of File Explorer. 4 Address bar Enables you to go to a different folder in the same Explorer window. (For more information, see Navigating the Address Bar in section 1.2.6.) 5 Column Titles of each of the columns displayed in the headings file and folder list. You can choose which columns you want to display by adding a column heading or removing a column heading, as well as changing the order in which those columns are displayed. Click on a column heading to sort your files and folders by that column (e.g. date modified). 6 Grade 9 Information Technology Student’s Textbook 6 Search box Allows you to search for subfolders, documents, images, programs, web pages and bookmarks in the current folder. 7 File and fold- Shows you the files and folders in the current folder er listing (the folder you selected in the Navigation pane). 8 Preview/De- Enables you to quickly preview an item, such as a tails pane photo, without having to open that item. To open the Preview pane (which is not open by default), click on the View menu at the top of File Explorer, then click on the Preview pane button located at the left-hand side of the Ribbon in the Navigation pane area. 9 Status bar Displays information about a selected folder and its contents such as the total number of items in the folder, the number of items selected and the total file size. Contains buttons that enable you to quickly switch between thumbnail and detail views for the items displayed in the current folder. Opening File Explorer To open File Explorer, click on the File Explorer icon located in the taskbar. Figure 1.5 Opening File Explorer from task bar Alternatively, you can open File Explorer by clicking on the Start button and then clicking on File Explorer. 7 Unit 1 : Organization of Files Figure 1.6 Opening File Explorer from Start menu You can use Win key ( ) + E keyboard shortcut to open file explorer. 1.2.2 Creating New File A file is created using a computer software program. For example, to create a plain text file you can use a text editor such as Notepad or Notepad++. You can use word processing software such as WordPad, Microsoft Word and LibreOffice Writer to create a text document file. An image file can be created using image editing software such as Microsoft Paint, Paint 3D, Gimp and Adobe Photoshop. Practical Exercise 1.1 Creating a document file 1. Work in a group to create a document file entitled Ethiopian Cultural Foods using Word processing software. Try to remember how to create documents using Microsoft (MS) word or any other word processing application software from your previous grade (Grade 8). 2. Open Word processing software on your computer. 8 Grade 9 Information Technology Student’s Textbook Figure 1.7 Newly created document 3. Type the passage To insert text in your document, place the cursor at the position where you want to enter the text and start typing a paragraph about the Ethiopian cultural foods by exploring different sources. You can see Figure 1.8 as an example document. Figure 1.8 Article on Ethiopian Cultural Food 9 Unit 1 : Organization of Files 4. Saving the document Save allows you to update a previously saved file with new content, whereas Save As allows you to save a new file or an existing file to a new location with the same or different name. How to create a text file The easiest way to create a text file in Windows is to open up the Notepad application software program on your computer. The Notepad is a text editor included with Microsoft Windows. A text file is considered as a plaintext file and Notepad is capable of creating and editing plaintext files. Notepad saves any text file with.txt file extension, which means no special formatting or fonts. The Windows Notepad program can be opened using the methods below. 1. Click Start. 2. In the Run or Search box, type Notepad and press Enter. Viewing, editing, and creating images There are many software programs you can use to display, view, edit and create images, logos or arts on your computer. Microsoft Paint is a default image editing application software in window Operating system. We can use it to simply edit our image file. Practical Exercise 1.2 Using Microsoft Paint to create an image Create an image using Paint application following the steps below. Click on Start Open Paint Application Create your own image Save your image 10 Grade 9 Information Technology Student’s Textbook Creating presentation file Presentation files are created for electronic presentations consisting of a series of separate pages or slides. To create presentation files, there are different application software such as Microsoft PowerPoint and LibreOffice. Practical Exercise 1.3 Preparing a presentation file for a project Work in a group to create presentation file using Microsoft PowerPoint (say Ethiopian Wild Life) using your previous grade (grade 8) knowledge of using Microsoft PowerPoint. Use the following steps to open it. 1. Open Microsoft PowerPoint application. 2. In the left pane, select New. 3. Select a New Blank Presentation. 4. Start adding contents in the slide about Ethiopian wild Life. 1.2.3 Creating a New Folder Creating a new folder can help you store related files in an organized manner. The following steps can be followed to create a new folder. 1. Navigate to the location where new folders are created. 2. In File Explorer, click on the Home menu item. 3. From the Home tab, click on the New folder button (See Figure 1.9). Figure 1.9 New folder button on file explorer 4. Enter the name of your new folder. 5. After you enter the folder name, click anywhere outside the text area to com- plete creation of the folder name. 11 Unit 1 : Organization of Files 1.2.4 Copying a File Copying a file is used to put the file in a duplicated manner. To copy computer documents, pictures or other files from one place to another, follow the following instructions. The following steps show how to copy a file or multiple files in Microsoft Windows from one folder to another. 1. Go to the files or folders you want to copy. 2. Highlight the file or files you want to copy by clicking them once with the mouse. If you need to highlight more than one file, you can hold down the Ctrl or Shift keys on your keyboard or drag a box around the files you want to copy. 3. Once highlighted, right-click one of the highlighted files and select copy. You may also press the Ctrl + C shortcut key or in File Explorer, click Home at the top of the window and click Copy. 4. Open the destination folder, right-click an empty space in the folder, and choose paste. Alternatively, in the File Explorer menu bar at the top, click Home and then click Paste. (See Figure 1.10). Figure 1.10 Copying a file using right click option 12 Grade 9 Information Technology Student’s Textbook When copying files, you are going to get more than one copy of the file on your computer. If you want only one copy of the files, move them instead. A file name must be unique; otherwise, a number will be appended to the end of a file name. It may also have “- Copy” appended to the end of the file name, instead of a number. Appending a number to the end of the copied file’s name assures the copied file is unique. For example, if the original file name is StudentMarkList.pdf and a copy is created in the same directory or folder, the copied file name could be StudentMarkList (1).pdf or StudentMarkList - Copy. pdf. 1.2.5 Renaming File and Folder You must have right or permissions to a file, a folder or a directory to rename it. In some cases, you may need administrator privileges in the operating system to rename. In Window, to rename files such as text, photo, document, audio and video files and folders, you can use one of the following methods. Method one 1. Highlight the file or the folder. 2. Right click the file with your mouse and select Rename from the menu that appears. Method two 1. Highlight the file or the folder. 2. Press the F2 key on the keyboard. Method three 1. Highlight the file or the folder. 2. Click File at the top of the window and select Rename from the list of available options. 13 Unit 1 : Organization of Files Method four 1. Highlight the file or the folder you want to rename by single-clicking the file. 2. Once highlighted, wait a few seconds and click the file name again. A box should appear surrounding the file or folder name, and you can rename the file. Figure 1.11 Renaming using right click Rename option If you do not wait long enough and click the file or folder too fast, it can open the file or folder rather than allowing you to rename it. If we want to rename multiple files of folders at once, we should keep the following steps. 1. Open Explorer. 2. In Explorer, select all the files you want to rename. 3. Once the files are selected, press F2 to edit the file name and type the new name for the files. For example, typing “test” renames the files to test, test (1), test (2), test (3), etc. If you have file extensions shown, make sure that you also typed the name of the file extension you are renaming. 14 Grade 9 Information Technology Student’s Textbook Figure 1.12 Renaming multiple files 1.2.6 Accessing Files and Folders There are a number of ways you can navigate to your files and folders in File Explorer. The methods below will help you to do so. Using the Address bar (located at the top of File Explorer). The Address bar shows the full path of your current location. Forward and Backward buttons From the Folders/Navigation pane Using the Search function (which searches file names and file and folder contents in the current folder to find items containing your search term) Using the address bar The address bar, which is located at the top of File Explorer as shown in Figure 1.13 below, displays the path of the currently selected folder or active folder. File Explorer drop-down menus are available for each subfolder in the address bar. Therefore, we can easily go backward or forward in the folder path by clicking on the right-pointing arrow next to the folder and selecting a subfolder from the drop-down menu. 15 Unit 1 : Organization of Files Figure 1.13 File Explorer address bar Viewing previously visited folders in the address bar To view folders you have seen previously, you can do any of the following. Option 1: Click on the forward ( ) or back buttons ( ) as shown in Figure 1.14. Figure 1.14 Forward and back buttons to view previously visited folders in address bar Option 2: Click on a folder name in the address bar as shown in Figure 1.15 below. Figure 1.15 Clicking on folder name to view previously visited folders in address bar 16 Grade 9 Information Technology Student’s Textbook Viewing the contents of a folder in the address bar To view the contents of a folder in the address bar, click on the right-pointing arrow ( > ) next to the folder whose subfolders you want to view. The arrow changes to a downward-pointing arrow ( V ) and a drop-down list of the subfolders will be displayed (See Figure 1.16). Figure 1.16 Viewing the contents of a folder in address bar 1.2.7 Displaying Subfolders Using Navigation/Folder Pane The Folders pane or the Navigation pane is found along the left edge of every folder and displays a directory tree of all the folders on your computer (See Fig- ure 1.4 and Table 1.1). You can select one or more folders in the Folders pane to display their contents in the File List pane. The Folder/Navigation pane contains several main sections: Quick Access, OneDrive, This PC and Network (See Figure 1.4). If you used previous versions of Windows 10, you know that a folder name would have a plus sign next to it if that folder contains documents or subfolders. With Windows 10, if a folder contains subfolders, that folder’s name will have a small right-pointing triangle next to it (>). No triangle next to a folder name ( ) means the folder has no subfolders. 17 Unit 1 : Organization of Files Right-pointing triangle next to a folder name ( ) means the folder has subfolders. Down-pointing triangle next to a folder name ( ) means the subfolders are currently displayed for that folder. To view a folder’s subfolders, click on the right-pointing triangle (>) next to the folder. The right-pointing triangle will turn into a down-pointing triangle and the subfolders will be displayed as shown in Figure. 1.17 below. Figure 1.17 Displaying subfolders In the figure above, “This PC” contains subfolders. To display the subfolders, just click on the folder name; to hide a folder’s subfolders, click on the down-pointing triangle of that folder so that the subfolders will no longer be displayed. 1.2.8 Moving Files and Folders on Computer There are several methods available to move computer files and folders (directories) from one source or level to another. When moving files or folders, only one copy of the files is moved. If more than one copy of the files are needed, copy the files and instead of move them. See how to copy files in section 1.2.4 above. In Windows, you can move files using several methods. These are: Cut and paste 18 Grade 9 Information Technology Student’s Textbook Drag-and-drop Use the “Move to Folder” command Below are the steps used in different methods (options) to move files in Windows. Choose the option that works best for you. You can also select multiple files and move multiple files at once using any of the steps below. Option 1: Cut and paste To move files using cut and paste method: 1. Select the file you want to move. 2. Right-click the highlighted file 3. Then select Cut. 4. Browse to the folder you want to move the file to. 5. Right-click in the folder, and select Paste. Figure 1.18 Moving a file in Windows 19 Unit 1 : Organization of Files Alternatively, you can click Home from file explorer, select Cut to cut the files, browse to where you want to move the files, then select Home and Paste in the file menu. You can also use shortcut keys to cut and paste files. Select the files you want to cut, then press the shortcut key Ctrl+X to cut the files. Cutting the files is like cutting text in a document, i.e. it moves the files to a temporary clipboard until you paste them somewhere. Navigate to the destination folder and press the shortcut key Ctrl+V to paste the files. The files are now in your destination folder. Option 2: Drag-and-drop To move the files and folders using drag and drop, follow these steps: 1. Highlight the files you want to move. 2. Press and hold your right mouse button and drag-and-drop the files to where you want to move them. 3. When you release the mouse button, a menu appears. 4. Select the Move here option to move the files. For drag-and-drop to work, you will need to be able to see the window of where you are moving the files. Option 3: Use “Move to Folder” To move the files and folders using Move to Folder command, follow these steps: 1. Select the file by clicking the file name. 2. Click the Home menu found on the top-left of the window and select the Move to Folder option. 3. In the new window, browse to the folder you would like to move the file; then click the Move button to move the file to that folder. If you are using Windows 7 and below versions, once the files are selected, the Move to option is shown under the File tab. 20 Grade 9 Information Technology Student’s Textbook Figure 1.19 Using Move to Folder command to move files 1.2.9 Deleting File and Folder Now and then, it is a good idea to clean up your drives and delete duplicated files such as photos, documents, temporary files and videos, and other unneeded or unwanted files and folders. The steps to delete a computer file, a directory or a folder vary based on the method you want to use and your operating system. Below are more common methods used for deleting a file or a folder in Microsoft Windows. Users not familiar with Windows should realize that if they delete a folder or directory, all files and folders in that folder or directory are deleted. Deleted files or folders can be restored from Recycle Bin if not permanently deleted using shift + Delete key. Use the following Steps to delete file or folders using Delete key method 1. Locate the item you want to delete. 2. Highlight the file or the folder by left-clicking with your mouse once. 21 Unit 1 : Organization of Files 3. Press the Delete key. You can delete multiple files or folders by holding down the Ctrl key and clicking each file or folder before pressing Delete. You can hold down the Shift key while pressing the Delete key (shift + Delete) to delete the files permanently. In this case, restoring from Recycle Bin is not possible since the file will not go to the Recycle Bin when deleted. It will be deleted permanently. Use the following steps to delete a file or a folder by right-clicking method. 1. Open This PC or File Explorer. We recommend you to make sure that the directory or folder is empty before proceeding; otherwise, you intend to delete everything in it. 2. Locate the file or the folder you want to delete and right-click it. 3. Choose the Delete option from the pop-up menu. Figure 1.20 Delete file using right click option Caution! The local disk contains files and folders that are important for your computer to run correctly. Unless you know what you are deleting, please do not delete any file from this section. 22 Grade 9 Information Technology Student’s Textbook Use the following steps to delete a file or a folder using Delete command from the Home menu. 1. Open This PC or File Explorer. 2. Locate and select the file or folder you want to delete. 3. Click Home in the top menu bar, and select Delete. Figure 1.21 Delete from the Home menu Practical Exercise 1.4 Find an icon of a file that you saved on your desktop before or identify any file that is not important anymore to keep and delete it using one of the methods that you have learnt. Caution: be aware of the danger of deleting system files. Note about a special folder called Recycle Bin where deleted files are kept in. You need to delete the file from the Recycle Bin for a permanent removal. 1.2.10 Searching a File on a Computer All major operating systems running on computers can find files on the hard drive or other drives connected to the computer. Microsoft Windows has a search feature that helps you find any file such as document, spreadsheet, picture or video on your computer. To find a file, it is not required to know its full name. Some of the methods used to search files are discussed below. Option 1: Using Start button 1. Press the Windows key; then type part or the entire file name you want to find. 23 Unit 1 : Organization of Files 2. In the search results, click the file name you want to open. Option 2: Using File Explorer 1. Open File Explorer. 2. In the left navigation pane, click Computer or This PC. 3. Near the top-right of File Explorer, click in the Search field and enter part or the entire file name you want to find. To find a file on a specific drive, click the drive under Computer or This PC in the left navigation pane. Then enter the file name you want to search for in the Search field. Figure 1.22 Search for a file in File Explorer Practical Exercise 1.5 Work in a group of two or three to do the following file and folder management activities. 1. Creating a folder Create two folders called Test1 and Test2 in Documents folder. 2. Creating files Create a text file and write the text “I love Ethiopian cultures” and save it as “testfile1.txt” in the Test1 folder created as answer to question number 1 above. Open the Test 1 and Test2 folders. Which of the two folders created above are empty? 24 Grade 9 Information Technology Student’s Textbook Create testfile2.txt in folder Test2 with the name of your school as a text following the above procedures. 3. Copying a file Copy testfile1.txt to Test2 folder using one of the methods you learned in section 1.2.8 above. What do you observe now in the two folders? Which folder contains two files? 4. Moving a file Move testfile2.txt from Test2 folder to Test1 folder. Which method do you use? Is there any difference between copying and moving files? What are the keyboard shortcuts that you use for copying and moving files? 5. Renaming a file Rename testfile2.txt file in Test1 folder as testfile3.txt. See section 1.2.5 to revise how you can do this. 6. Deleting duplicated file Notice that we have a file named testfile1.txt both in Test1 and Test2 folders. Thus, the file is a duplicate. What is the problem of keeping duplicate files in your computer? Remove testfile1.txt from Test2 folder. Open the Recycle Bin and search for the testfile1.txt file. Why is it found in the Recycle Bin? KEY CONCEPTS ✍ File Explorer enables you to create, view, rename, delete and search files and folders in computer. ✍ File Explorer is also called Window Explorer in earlier versions of Windows 10. ✍ You can use window key + E to open File Explorer. 1.3 Computer Drives A drive is a computer hardware component used to store and retrieve data, files, programs, operating system, etc. All drives store files and programs used by a computer. For example, when you write a letter in a word processor, the program is loaded from the hard drive. When you save the document, it is saved to the 25 Unit 1 : Organization of Files hard drive or other disk or drive. In window operating system, a drive is often referred to by its letter like C:, D: or F:. However, Linux operating system uses tree structure starting from root represented by forward slash (/). For example, / home in Linux is a directory used to store users files. A computer drive can be a hard disk drive, CD/DVD drive, removable disk (USB) flash drive, etc. These are called secondary storage devices which you have learnt in Grade 8. A hard disk drive (hard disk or fixed disk) is usually designated as the “C: drive”. The hard disk drive is the main data and program storage hardware device that can provide quick access to large amounts of data and program in a computer. A CD/DVD drive, which is also called optical disc drive, allows you to use CD and DVD to listen to music, watch movie or store any files. It is usually designated as the “D: or G: drive”. A USB drive, which is also referred to as a flash drive or memory stick, is a small, portable device that plugs into the USB port on your computer. USB drives are commonly used for storage, data backup and transferring files between devices. The following figure shows examples of common computer drives. Figure 1.23 Computer drives Some users may be confused with “drive” and “driver.” These are separate terms. The word drive typically refers to a mechanical hard drive or solid-state hard drive used to store the operating system, data 26 Grade 9 Information Technology Student’s Textbook and programs. A driver is software code that enables one or more hardware devices to communicate with the computer’s operating system. Without drivers, a computer could not send and receive data correctly to hardware devices such as printer and flash drive. Accessing all drives available on a computer In Windows 10, it is possible to view all mounted or attached drives in File Explorer. To achieve this, follow the following steps carefully. 1. Open File Explorer by pressing Windows key + E. 2. In the left pane, select This PC. 3. All drives are shown on the right. Figure 1.24 shows a typical view of This PC with three mounted drives. Figure 1.24 This PC in Windows 10 27 Unit 1 : Organization of Files Practical Exercise 1.6 Work in a group of two or three to practice accessing removable drive and copying files from it following the instructions given below. Plug a removable drive and copy any file into a folder created in your Documents folder. Note for safe removal of a flash drive. When you have done using a flash drive, do not remove it from the USB port just yet! You will need to make sure that it is disconnected properly to avoid damaging files on the drive. Follow is the steps below to safely remove your flash drive. 1. Right-click the flash drive; then select Disconnect (or Eject) disconnecting the flash drive. 2. You can now safely remove the flash drive from the USB port. If you want to rename a flash drive, follow these steps 1. Right-click the flash drive; then select Rename. In Windows, most of your programs are stored in the Program Files folder, and your documents are frequently saved in the My Documents folder. MINI PROJECT: MANAGING FILES, FOLDER AND DRIVES Read and understand each of the following cases carefully and answer the questions that follow them. Case 1 Suppose you have just started to work in school as record officer. Your computer uses Windows 10. Your first task is to organize the hard drive on your computer. Record officer create and save several types of files about the students, including words, spreadsheets and pictures. Your supervisor has asked you to present a plan for organizing the student files on the computer. Currently, all of the files are saved in the root directory or folder of the computer. 1. Write a plan for naming and organizing the students’ files of the school. Include the following in your plan. 28 Grade 9 Information Technology Student’s Textbook a. Create a visual tool using pen and pencil that explains your plan. b. Create a list of folders and describe how you will identify each folder and the files that are to be placed in each folder. For example, you might organize files by students’ year or section. c. Create your own naming standard for folders and files. For example, the name can contain student grade; then underscore the section, i.e. Grade_Section. 2. Create all the necessary folders and then files according to the above plan. 3. Show the new filing system to your teacher. Describe how you will use File Explorer to view the new folder structure and the organized files for students’ registration files. Case 2 Suppose you use computer to store all information about the subjects you are currently learning. For example, you may have notes, reference books, assignments and files or folders for each subject. 1. Write a plan for naming and organizing the subjects you have been learning in grade 9. Include the points discussed above in case 1 in your plan. 2. Create all the necessary folders and then files according to the above plan. 3. Show the filing system you have created to your teacher. KEY CONCEPTS ✍ Drive is a hardware component of a computer which stores files and folders. ✍ Drive can be fixed and removable. ✍ Fixed drives are found within a computer while removable drives are portable and plugged externally. ✍ This PC section of Window Explorer navigation part contains all drives mounted on the computer. 1.4 Unit Summary Learning files and folders is important. Organizations, small or large, have file management systems either in a computerized or manual system. Organization 29 Unit 1 : Organization of Files maintains different files such as human resource data, day-to-day activity data, payroll files, customers’ files, organizational documentation files, plan and schedule. Students must know how to manage files and folders in a computer system so that they can easily locate it, search it, organize similar file together in a folder, delete unwanted file to make a room for important files, and do similar activities on files and folders. The following are key points of files and folders organizations. A file is a collection of similar data stored in a computer system. A file in computer is analogous to real world file which is used to store some data, for example, student’s data, teacher’s data, etc. In computer, file can be document, picture, audio, video, application, etc. Each file in a computer has unique icons. A folder is like manila folder, it is a container of a file and other folder. Folder helps you organize similar files together so that you can locate files in a computer easily. File explorer is the best application in order to manage files and folders in window. Managing files and folders includes creating, deleting, renaming, sorting, viewing and similar activities on files and folders. Navigation Pane is part of the File Explorer which is used to view your computer files and folders in tree structure hierarchically. It consists of quick access sections: OneDrive, This PC and Network. Quick access section is used to navigate to folders quickly. It consists of Desktop, Download, Documents, Pictures and frequently accessed folders. If you click Desktop, you will get all files found in your desktop. Browsers such as Internet Explorer, Microsoft Edge and Chrome will put all files downloaded from internet by default in Download folder. So, you can access your Download file from Quick access section in navigation pane. Documents contains word documents, letters, memos, etc. and Picture contains photos you have shot or saved from the Internet. To open File Explorer application, you can use: The shortcut on task bar or on the desktop. 30 Grade 9 Information Technology Student’s Textbook Start typing ‘File explorer’ after clicking Start button. Window key + E keyboard shortcut. To navigate to your files and folders using File Explorer in a computer system, you can use either of the following methods. Using the Address bar (located at the top of File Explorer) Forward and Backward buttons of File Explorer From the Folders/Navigation pane Using the Search function which is located at the right side of File Explorer Clicking the right-pointing triangle next to the file on navigation pane, to view the subfolders and/or content of each folder To move files, you can use either of the following methods. Cut and paste Drag-and-drop Use the “Move to Folder” command You can use F2 shortcut key to rename file or folder after selecting it. A drive is a computer component used to store the data and it can be: Static (built in) drive: including internal hard disk, SSD and the like. Removable drive: including Flash Disk, Removable Hard Disk, CD, etc. To view all mounted or attached drives in window, File Explorer application is used. 1.5 Unit Review Exercise Part I: Write whether the following statements are true or false. 1. ‘Copy and paste’ can also be referred to as moving a file. 2. A file is an entity in a computer system that contains other files inside. 3. Renaming a file removes its content. 31 Unit 1 : Organization of Files 4. Dragging a file creates multiple copies of files. 5. Deleting a file will completely remove files from the disk. 6. We cannot access or open files and folders using address (path) because files and folders do not have address in computer. 7. Windows does not allow handling multiple files. Part II: Choose the correct answer among the alternatives provided. 1. To expand a branch of the folder tree, you would _____. A. click on the folder name in the folder tree B. click on the icon Arrow right (>) of the branch C. click on the icon Arrow – down (V) of the branch D. None of the above. 2. To remove a file or a folder, you would _____ A. drag it out of the window B. select it and press the Delete key C. select it and press Ctrl + Delete keys D. right click on the file or the folder and select Cut 3. What do you do to select an of icon a file? A. Left click B. Right click C. Double click D. Scroll 4. Which one of the following is true about file explorer? A. It was called window explorer previously. B. It is used to view files and folders. C. It is used to view available drives. D. All of the above. 32 Grade 9 Information Technology Student’s Textbook 5. What do you do to get a menu when clicking on a folder or file icon? A. Left click B. Right click C. Double click D. Scroll 6. Which type of icon can take you to another place quickly? A. File B. Folder C. Application D. Shortcut 7. What do you do to open a folder? A. Left click B. Right click C. Double click D. Scroll 8. What do you do to rename a folder? A. Left click B. Right click C. Press F2 key D. Scroll 9. What is drive used for? A. To open files from your teacher B. To use applications not on your computer C. To save things on the computer D. To save their work for students 10. What would you do to see the content of the file using Navigation pane? A. Right click B. Left click C. Double click D. Drag 33 Unit 1 : Organization of Files 11. _______is used to open a file or a folder. A. Right click B. Left click C. Double click D. Drag 12. Which one of the following short cut keys is used to save any file? A. Ctrl + N B. Ctrl + S C. Alt + Z D. Ctrl + A Part III: Fill in the blanks. 1. Information is stored in a storage device with a specific name called __________. 2. Duplication of files from one drive to other is called _______________________. 3. The cut and paste option is also called _______________________. 4. ______________________ means locating a file among a set of files. 5. To delete a file, you have to click the right button of the mouse on the file name and select the _________________ option. 6. __________________ is used to manage files and folders in window. 34 Grade 9 Information Technology Student’s Textbook Part IV: Match the following items in column A with column B. A B 1. Collection of data A. File Explorer 2. Used to organize similar files B. Used to draw pictures 3. Used to manage files and folders C. Navigation panes 4. View your computer’s file and folder structure D.Used to process text files 5. Formerly called favorites E. File 6. Allows you to see all networked PCs F. Quick Access 7. Paint Application G. Network 8. Moving files H. Folder 9. Fixed drive I. CD J. Internal hard disk K. This PC L. Copy and Paste M. Cut and Paste N. Internet Explorer Part IV: Provide clear and precise responses to the following questions. 1. What is the difference between a file and a folder? 2. Where are files stored? 3. Write the steps to create a folder? 4. Why do files need to be kept in the proper place in a computer? 5. Write the major steps to rename a folder? 6. Write the major steps to delete a folder? 35 Unit 2 : Computer Network UNIT 2 COMPUTER NETWORK UNIT OUTCOMES At the end of this unit, learners will be able to: Define what a computer network is. Identify the building blocks of a computer network. Compare and contrast the basic types of networks (LAN, MAN, WAN) and client server vs. peer to peer. Describe the topologies of network. Discuss the advantages and disadvantages of network. Draw simple network diagrams using network device symbols. UNIT OVERVIEW This unit focuses on computer network, mainly on Internet and Internet services emergence. You learned about Internet and its services in grades 7 and 8. Do you remember the different services that you can get from the Internet such as web surfing for searching information, file sharing, chatting, messaging, and social media networks? There are also serious risks associated with unsafe and improper utilization of Internet. This unit discusses fundamental concepts of computer network. The unit is divided into four sections. The first section defines what a network is and is followed by listing and describing different components of a computer network, both the software and hardware parts. The last two sections present types of network and advantages and potential threats of connecting computers or other electronic devices into a network. 36 Grade 9 Information Technology Student’s Textbook 2.1 Definition of Network Brainstorming 1. Have you shared a file or received a message using mobile phone? How do you think that your file or message move around to reach its destination? 2. Identify different organizations in your local areas that utilize computer networks for their service provisions. A netwok is a connection of two or more computers that are linked together in order to share resources(such as printers, files and disks) or allow electronic communications. Using Bluetooth application in your mobile phone to share files is an example of a network.Sometimes, the Internet is called the largest global network. Figure 2.1 shows an example of a network with multiple computers and other network devices, which are all, connected. The figure shows that the laptop, the tablet, the mobile phone and the television are connected to the central network device. The central network device is, in turn, connected with a global network through an internet service provider (ISP) company such as Ethio- telecom. You will learn more about these in the next sections. Figure 2.1 Home network 37 Unit 2 : Computer Network Activity 2.1 Form a group of three to five students and discuss the following questions. 1. What is a computer network? 2. What are the applications of network in our day-to-day lives? 2.2 Fundamental Elements of Network Networks are comprised of four basic elements: hardware, network software, protocols and connection medium. All data networks are comprised of these four elements, and cannot function without them. The backbone of any network is the hardware that runs it. As you can see from the top two rows in Figure 2.2 below, network hardware includes end devices and intermediary devices. Network software is also a foundational element for any network. This type of software helps to manage connected end devices and services the network provides. Protocols are set of rules to facilitate electronic communication across connected device. You will learn more about protocols in Grade 10. Transmission medium which can be wired or wireless, caries message between end devices. Each element of networks is described one by one in section 2.2.1 to 2.2.4 below. Figure 2.2 shown in the next page presents examples of the hardware elements in the three categories. 2.2.1 End Devices Brainstorming Consider different electronic devices at home, e.g. digital camera, laptop, mobile, television, etc. Which of the devices do you see connected with cable or other formats? 38 Grade 9 Information Technology Student’s Textbook End devices, which are also called hosts, are devices used to send or receive data over the network. The sending device is called a sender and the receiving one is a receiver. Some examples of end devices are: Computers(such as desktops, laptops, file servers and web servers etc.) Network printers Security cameras Mobile handheld devices. Figure 2.2 End devices, intermediary devices and media 2.2.2 Intermediary devices Intermediary devices interconnect end devices. These devices interconnect and work behind the scenes to ensure data flow across the network and the devices. Intermediary devices connect the individual hosts to the network and also can connect multiple individual networks to form an internetwork. Intermediary device includes network cards, routers or network switches, wireless access point (WAP) and repeaters. Without these hardware devices, end devices have no means of accessing a network. a. Network Interface Card (NIC) Network Interface Card (NIC) is a computer hardware component that connects a computer to a computer network. As it is shown in Figure 2.3, Network Interface 39 Unit 2 : Computer Network Card (NIC) comes in a card form to be plugged into the computer system or can be an integrated one as part of the systems board that you often see in laptops. NIC has a slot to plug-in a cable connection with a network. Figure 2.3: a) Network interface card b) Cable to be plugged in to a desktop computer NIC b. Repeater Communication media or cables that you are going to learn in section 2.2.4 have limitation. This includes the electronic signal they carry will become weak after traveling a long distance. Repeater enables a network segment to extend the coverage to reach beyond its inherent distance limitation by refreshing or generating the weak network signal. Figure 2.4 depicts that a weak signal (depicted on top of the Figure) is regenerated by a repeater in the middle to restore the signal to its original signal (bottom). Figure 2.4 Repeater 40 Grade 9 Information Technology Student’s Textbook c. Switch A switch, as shown in Figure 2.5 (a), is a device that interconnects various devices such as computers, printers and servers in a small business network, as shown in Figure 2.5 b below. Switch is more intelligent device than hub as it can segment a computer network into smaller parts. In addition, switch forwards packets to specific destination after learning the network topology. To perform this, switch uses a table which contains computer physical address and switch port number on which a computer connected on. A hub is unintelligent device which broadcasts all received packets to all computers connected to it except the sender. Figure 2.5 a) 24 port switch b) Switch on a network d. Router Consider yourself as a taxi driver in a given town which has a lot or streets (roads) interconnected. Think about the driver when he or she selects a particular street from many different options available to reach to his or her destination. What factors does he or she consider? The distance? The traffic jam or number of cars in a certain road segment? Which road segment would take him or her where? What else, he or she might think of? A router is such an intelligent device which operates in determination of pathways for electronic messages in networks. A router, as its name suggests, works with routing or finding a route through a network. That is, it is a router of a network. The main objective of router is to connect dissimilar and different networks simultaneously as shown in below Figure 2.6. As shown in the figure, there are two network segments, each connected to a switch. The two switches are connected to each other through the router. Assume two different cases. 41 Unit 2 : Computer Network Case 1: A computer sends a message for another computer within one network; that is, both the sending and the receiving computers are connected to the same switch. Case 2: A computer in one network segment sending a message to another network connected to a different switch. The router usually works for case 2 type scenario and it selects best route to reach to the destination network. To do this, a router uses a mechanism called routing table, which contains destination network field and interface number of routers. Figure 2.6 Router connecting two networks e. Wireless Access Points Brainstorming Discuss in a group of three to five students about different methods that you could use to connect handheld mobile phones to the Internet. 42 Grade 9 Information Technology Student’s Textbook A wireless access point (WAP) is an intermediary device in a network that connects various types of wireless communication devices with wireless networks. The connectivity is made possible through Bluetooth and Wi-Fi technologies. It acts as an intermediary between wireless and wired devices that are part of a network (See Figure 2.10 in Section 2.3). 2.2.3 Communication Protocol Brainstorming 1. Do people have a convention, protocol or set of rules when they communicate, for example when they talk on phone or write a letter, email, etc.? Have you learned about formal and informal letter writing in your English or local language subjects? How do you write sender’s and receiver’s addresses in the letter? Are these not protocols? What others common protocol do you remember? 2. What will happen if an individual does not follow a protocol? In networking, a protocol is a set of rules that governs data communications. In order for different network hardware to interact with the network, they should follow the same rules called protocols. It is software that instructs network devices on how to connect to the network and how to interact with one another. Internet Protocol (IP) is one of the important communication protocols and used for addressing network devices and forwarding data from one network to another. You will learn IP and its classes in detail in grade 10. 2.2.4 Connection Media Brainstorming Why are the telecommunication cables stretched across the streets and roads? What about the big mobile antenna towers that stood on the hills and in the towns? Without physical connections(wired or wireless), a network cannot function. The connection media are the media which are used to carry the message from sender to receiver. We have two types of communication medium: wired and wireless. 43 Unit 2 : Computer Network i. Wired medium: It is also called guided medium. It is a cable that connects end devices. Copper and fiber optic cables are examples of wired medium. The most common copper cable used in networks today is unshielded twisted-pair cable (UTP), which uses electric signal to transmit message for a maximum distance of 100 meters. Fiber optic cable uses light to transmit signal at faster speed and longer distance than copper cable. ii. Wireless Medium: It is also referred to as unguided media or unbounded transmission media. It is used to communicate information through the air, water or vacuum, e.g. radio Waves, micro waves, infrared waves and satellite communications. Figure 2.7 below presents some examples of wired and wireless communication media along with their connectors. You will cover the communication media in detail in grade 10. Figure 2.7 Types of communication medium 44 Grade 9 Information Technology Student’s Textbook Activity 2.2 Form a group of three to five students and work on the following activities. 1. Visit your school network or computer laboratory and identify fundamental elements of network available. 2. Ask the network administrator or the laboratory manager about some network protocols used/implemented in the design of the school network? 3. Find an unshielded twisted-pair (UTP) cable analyse its connectors, the number of wires inside the plastic shield, colour of each wire and order of the colours. 4. Ask the responsible person about which interconnecting devices are used to set-up the network at your school and roles or functionalities of the devices in the school’s network. 5. Compile an activity report and reflect it in your class. Practical Exercise 2.1 Form a group of two to three students and work on the following activities. 1. Search the internet for Cisco and Huawei network device symbols that are covered in the classroom. 2. Use these symbols and draw simple network diagram that consists of the fundamental elements of network 3. Draw a network diagram specified in Figure 2.6 using a Cisco packet tracer, Graphical Network Simulator 3 (GNS3) or on paper using the right symbols. KEY CONCEPTS ✍ Network is connection of two or more devices for sharing resource which can be data, hardware, software, etc. ✍ A given network comprised of the following four basic components. 45 Unit 2 : Computer Network End devices are senders and receivers and able to send and receive messages. Intermediary devices are used to interconnect end devices together in the same and different networks. Protocols are common rules followed by communicating parties to govern communication in a network. Transmission medium is a physical path between sender and receiver, used to carry message. ✍ There are two types of transmission medium: wired and wireless medium. ✍ Switch is used to create a local area network whereas Router is used to interconnect different local area networks. 2.3 Types of Networks Brainstorming Consider networks at your home, if any, or at your school. Consider also the network that belongs to such a big company, like Ethiopian Airlines, that has branch offices throughout Ethiopia and abroad. Are the network technologies and number of end devices connected the same among these networks? Discuss how they are the same or different. There are different types of network classified based on the following four cate- gories: Network media Size of the network or geographical coverage of the network Topology Resource security and access The type of network based on this categorization is depicted in Figure 2.8 below. Each type of the network depicted in Figure 2.8 is discussed in subsection 2.3.1 to 2.3.4. 46 Grade 9 Information Technology Student’s Textbook Figure 2.8 Types of networks based on different perspectives 2.3.1 Types of Network Based on Connection Medium Based on connection medium, computer networks are classified into wired and wireless networks. Wired Network Wired networks, also called Ethernet networks, are the most common type of local area network (LAN) technology. A wired network is simply a collection of two or more computers, printers, and other devices linked by Ethernet cables. This is shown in Figure 2.9, as an example, where each line connects the end devices and servers to the global network (the globe) cables. Figure 2.9 Wired network 47 Unit 2 : Computer Network Wireless Network If you compare Figure 2.10 below, which is a wireless network, with Figure 2.9 above, you will see a wireless access point connecting with a wireless or a wired computer and a model, which connects the network with the Internet (or cloud). Wireless networks have no physical connection with the wired network; instead they get connected through the wireless access point (WAP). A wireless network, which uses high-frequency radio waves rather than wires to communicate between nodes, is another option for home or business networking. Individuals and organizations can use this option to expand their existing wired network or to go completely wireless. Wireless network allows for devices to be shared without networking cable which increases mobility. Figure 2.10 Wireless network 48 Grade 9 Information Technology Student’s Textbook The backbone of wireless network is always a wired network. Activity 2.3 Ask your parents or adults you have close contacts with about the following and discuss them in your classroom. 1. Ask your parent or any person about different networks which exist in your city, town or village. 2. Based on the description you got from your activities in question number 1 above, discuss the types of the network that at least one of the organizations has in terms of connection medium, wired, wireless or a mixed one? 3. Discuss also what types of end and intermediary devices the network could potentially have in the organization, with a reason for your device type selections. 2.3.2 Types of Networks Based on Size Computer networks can be characterized by their sizes. The size of a network can be expressed in terms of the geographic area the network occupies and the number of computers connected to the network. Networks can cover anything from a handful of devices within a single room to millions of devices spread across the entire globe. In Figure. 2.11 and Table 2.1, we classify networks by their rough physical size. The smallest in size is the personal area networks (PAN), networks that are meant for one person. Beyond PAN, with varying coverage range are categorized into local, metropolitan and wide area networks, each with increasing scale. Some of the network types based on size are: Personal area network or PAN Local area network or LAN Metropolitan area network or MAN Wide area network or WAN 49 Unit 2 : Computer Network Figure 2.11 PAN, LAN, MAN and WAN Table 2.1 PAN, LAN, MAN and WAN Descriptions Network Distance 1m Square Mater Personal Area Network 10 m Room Local Area Network 100 m Building 1 km Campus 10 km City Metropolitan Area Network 100 km Country 1000 km Continent Wide Area Network 10,000 km Planet Personal Area Network (PAN) A personal area network (PAN) is a computer network organized around an individual person within a single building. A common example is a wireless network that connects a computer with its peripherals. Almost every computer has an attached monitor, keyboard, mouse and printer. If there is no wireless network, this connection must be done with cables. 50 Grade 9 Information Technology Student’s Textbook A network created by Bluetooth is PAN. Bluetooth is a short-range wireless network used to connect computer’s peripheral components without wires as shown in Figure 2.12. In the figure, a laptop, a mobile phone and a television or tables are connected to one another without a cable. The idea is that if your devices have Bluetooth, then you need no cables. You just put them down, turn them on and they work together. Figure 2.12 Bluetooth PAN configuration This type of network provides a great flexibility. For example, it allows you to: Send a document to the printer in the office while you are sitting on the couch with your laptop. Upload a photo from your cell phone to your desktop computer. Watch movies from an online streaming service to your TV. Local Area Network Local Area Network (LAN) is generally an organizational or a privately owned network within a single office, building or campus covering a distance of a few kilometers. The main reason for designing a LAN is to share resources such as storage spaces, printers, programs and data. It also enables the exchange of information. The smallest LAN may use only two computers while larger LANs can accommodate thousands of computers. A LAN typically relies mostly on wired connections for increased speed and security, but wireless connections can also 51 Unit 2 : Computer Network be part of a LAN. If a LAN is entirely wireless, it is referred to as a wireless local area network (WLAN). Figure 2.3 depicts a LAN that combines cabled and wireless networks into a single network. Figure 2.13 Wired and wireless and local area networks Metropolitan Area Network A Metropolitan Area Network (MAN) is a network that is designed to cover an entire city. Suppose a bank wants to connect three of its branches in a given city. In such a case, the bank will utilize the service of existing telephone network of the city (for example the Ethio-telecom network) to interconnect its offices, through which MAN is created. Figure 2.14 shows a MAN that interconnects a hospital, a school/collage and a factory local area networks. 52 Grade 9 Information Technology Student’s Textbook Figure 2.14 Metropolitan area network Wide Area Network A wide area network (WAN) occupies a very large area such as an entire country or the entire world. A WAN can contain multiple smaller networks such as LANs or MANs. The Internet is the best-known example of a public WAN. A diagram depicting MAN is shown in Figure 2.15 below. It indicates that computers residing in different parts of the world are connected to each through a MAN. Figure 2.15 Wide area network 53 Unit 2 : Computer Network Activity 2.4 Do the following as an extension to Activity 2.3 above. Based on the description you got from your activities in question number 1 of Activity 2.3, discuss the type of the network that at least one of the organizations has in terms of connection medium as well as size of the network. 2.3.3 Types of Network Based on Topologies Network topology defines how various computers or electronic devices represented as nodes are connected to one another in the network. It refers to the physical arrangement of devices in a network. Typical network configurations include bus topology, mesh topology, star topology, and ring topology (See Figure 2.16). Figure 2.16 Network topologies a. Bus Topology In bus topology, there is a long cable called bus which acts as a backbone for all the nodes as shown in Figure 2.17. A bus topology network connects each computer or electronic devised to a backbone cable (or bus) just like a water pipe interconnections. Figure 2.17 Bus topology 54 Grade 9 Information Technology Student’s Textbook A bus is easy to install and uses less cables than other topologies. However, fault isolation becomes very difficult in bus topology. It is also relatively difficult to add new nodes to a bus, thus making it more inflexible. This is because addition of a node changes the number of taps and the average distance between them, which are generally optimized for a bus length. Another demerit is that, even if a portion of the bus breaks down, the whole bus cannot function. b. Mesh Topology In mesh topology (also called complete topology), each node is connected to every other node by direct links. Figure 2.18 illustrates this. Mesh topology does not have traffic congestion problems due to dedicated links. This topology has the advantage in terms of data security. It is also robust; that means, if one link is down, the rest of the network can still continue. Fault identification is also easy in this case. The main demerit of this network scheme is cable length and consequent cost and complexity. This is clearly impractical for medium to large networks. Figure 2.18 Mesh topology 55 Unit 2 : Computer Network c. Star Topology In a star topology, each device has a dedicated point-to-point link only to a central controller, usually called a switch. The devices are not directly linked to one another. Unlike a mesh topology, a star topology does not allow direct traffic between devices. If a node wants to send some data to another node, it sends it to this switch. The switch, in turn, sends it to the appropriate node as Figure 2.19 depicts. Star topology is cheaper than mesh topology. It is also relatively easier to install, maintain and reconfigure. It is also robust. However, if the switch goes down, the entire network becomes defunct. This is a major demerit of this scheme. Figure 2.19 Star topology d. Ring Topology In ring topology, each node is directly connected to only its two adjacent neighbors. If a node wants to send something to a distant node on a ring, it has to go through many intermediate nodes, which act like repeaters, reproducing the incoming bit stream with full signals on the outgoing line. Figure 2.20 depicts this topology. 56 Grade 9 Information Technology Student’s Textbook Figure 2.20 Ring topology A ring is easy to reconfigure and install. In a ring, a signal normally circulates all the time. A node not receiving any signal for a long time indicates a fault. Therefore, fault isolation is relatively easy in a ring. However, if a node in a simple ring fails, the whole ring cannot function. Another demerit is that traffic flows only in one direction. This topology is not used if the number of nodes to be connected is very high. Advantages and disadvantages of all network topologies are summarized in below Table 2.2. Table 2.2 Advantages and disadvantages of all network topologies Topology Advantages Disadvantages - Difficult to reconfigure - Cheap Bus - Break in bus disables entire net - Easy to install work - Cheap - Easy to install Star - More expensive than bus - Easy to reconfigure - Fault tolerant - Efficient - Reconfiguration is difficult Ring - Easy to install - Very expensive - Extremely difficult for reconfigu- - Simplest ration Mesh - Most fault tolerant - Extremely expensive - Very complex 57 Unit 2 : Computer Network Activity 2.5 Do the following as an extension to Activities 2.3 and Activity 2.4. Based on the description you got in Activity 2.3 question number 1, discuss the type of the network that at least one of the organizations has in terms of connection medium, size and network topology. 2.3.4 Types of Network Based on Resource Security and Access Peer-to-Peer Network In a Peer-to-Peer network, each machine (computer) is known as peer and can participate in the sharing of files or resources. No server is required in this network, so there is no additional cost for a dedicated machine, but there is also no a real security. A peer-to-peer network is also called workgroup and there is no hierarchy among the computers. This mean that all computers are peers (equals) and the connection is created for resource sharing and communication purposes only. The number of computers in peer-to-peer network usually does not exceed 10; if the number is beyond this, the network becomes very difficult for administration. Advantages of peer-to-peer network Server is not required. All computers are equal in the network. No additional cost is needed for dedicated-machine. Disadvantages of peer-to-peer network Provides share level security, i.e. it applies a trust-based security. Can work in small environments only. Client-server Network A client-server network involves multiple clients or workstations, connecting to at least one central server. Most resources are installed on the server. When clients need access to these resources, they access them from the server. Servers often have private user directories as well as multiple public directories. 58 Grade 9 Information Technology Student’s Textbook In client-server networks the clients are allowed to function as workstations without sharing any resources. It is easier to upgrade software applications and files because they are held on one single computer. System-wide services can be provided through the server software. Security is enhanced on a client server network because the security is handled by the server. The following table sum- marizes the difference between peer-to-peer and client network. Table 2.3 Comparison of client-server and peer-to-Peer networks S.No Client-server Network Peer-to-peer Network Clients and server are differentiated; Clients and server are not dif- 1 specific server and clients are present. ferentiated. 2 Focuses on information sharing. Focuses on connectivity. Centralized server is used to store the 3 Each peer has its own data. data. Each and every node can do Server responds the service which is 4 both request and respond for requested by client. the services. Less costly than client-server 5 Costlier than peer-to-peer network. network. More stable than peer-to-peer net- Less stable if number of peer is 6 work. increased. A client is a computer which requests resources and services while a server is a computer which provides services and resources according to client requests. Informally, clients often tend to be desktop PC’s or workstations, while servers are more powerful machines. KEY CONCEPTS ✍ There are different types of network based on type of medium, topology and size of the network, and resource security and access. ✍ Wired network uses cable while wireless uses radio waves to form a network. 59 Unit 2 : Computer Network ✍ The number of devices connected in the network and the geographical coverage of the network is called the size of the network. ✍ Based on size of the network, network can be categorized as personal area network (PAN), local area network (LAN), metropolitan area network (MAN) and wide area network (WAN). ✍ Network topology is the physical arrangement of devices on a network and can be bus, star, ring and mesh topologies. ✍ Based on security and access, network can be either client-server or peer-to- peer network. Activity 2.6 Ask your parents or adults you have close contact about the following and discuss them in classroom. 1. Discuss whether peer-to-peer or client-server network is more appropriate for: a. A small home network. b. A school laboratory network. 2. Discuss advantages and disadvantages you considered for the selection of the network type in question 1 above. 2.4 Advantages and Disadvantages of Network Brainstorming Consider networks at your home, if any, or at your school. Discuss the potential benefits as well are risks that emerge from connecting to a network. 60 Grade 9 Information Technology Student’s Textbook 2.4.1 Advantages of network There are more advantages to a network than disadvantages. In fact, many companies today would not exist without accessing some form of network. Below are the advantages of a network. Sharing data and information - One of the biggest advantages of a network is sharing data and information between each of the devices on the network. In addition, networks allow accessing the data which is stored on central computer called database server. For example, we use network for sharing documents, images, photos, songs and videos. Communication - A network gives all users the ability to quickly communicate with each other either using chatting or instant messaging services such as Skype, WhatsApp and Viber to send files and messages among the users, video conferencing, e-mail, TV and radio. Communication at a distant is called telecommunication; ‘tele’ in Greece is to mean remote. Sharing hardware – Expensive hardware devices connected to a network can be shared among all users. Storage devices such as Hard Disk that are shared on a storage server, which is also called NAS (Network attached storage), can store and access vast amounts of information. A printer which is attached and shared on a server (printer server) allows all network users to print from one printer according to their privilege configured on the server by a network administrator. Fax machines, Scanners, more powerful computers, such as super computers that can perform complex tasks within short period of time than a single computer will take to complete. Share software – Different application software and Internet-based services can be shared over the network for all licensed users for the software. For instance, we can share software such as computer games and work Internet-based services such as e-learning. E-learning or learning management system in its broadest sense is designed to support 61 Unit 2 : Computer Network teaching and learning as well as student-to-student and student-to- teacher instructions. Transferring money - Being connected to a secure network allows a person or business to digitally transfer money between banks and users. For example, a network could allow a company not only to manage employees’ payroll but also to transfer their pay to the employee’s bank account. 2.4.2 Disadvantages of network Although there are many advantages to a network (mentioned above), there are some disadvantages. Below are some disadvantages of a network. Virus and malware - Networks make sharing information between network users easy. Unfortunately, this also means that viruses and other malwares have an easier time spreading between computers on a network. Vulnerabilities - When computer are connected on the network, it will be accessible remotely, with these potential new methods of accessing the computer; it can introduce new security issues or vulnerabilities to the computer, users and the data on the network which affect the organization and the country at large. Complex - Networks are complex, and setting up and managing a network for a business or corporation requires someone with a lot of experience or certification. Cost - Setting up, managing and administering a network hardware and software incurs cost to the organization building a network. Social media effect on youth and adults - particularly youths, including students, waste their time on use of social media and unsafe Internet resources. There are also many cyber security threats such as cyberbullying, disinformation/misinformation and identity theft that you should be aware of and learn to develop safe use of the Internet. 62 Grade 9 Information Technology Student’s Textbook Practical Exercise 2.2 Make a group of three to five students and do the following. 1. From Ethio-telecom website (https://www.ethiotelecom.et/), assess the common network services it provides as an internet service providers (ISP). 2. Search for reliable information such as the one from Ethiopian Information Network Security Agency (INSA) https://www.insa.gov.et) about different cyber security attacks that you may encounter as a student – such as misinformation/disinformation, cyberbullying, sex trafficking, hate crime and financial scams. Discuss in group how you can protect yourselves from such attacks. 3. Explore the functionalities and symbols used for representing network devices, preferably in an open source network mapping tools such as Dia (http://dia-installer.de/). KEY CONCEPTS ✍ Computer network can be used to exchange data and information, and to share resources such as hardware (e.g. storage spaces) and software. ✍ A virus can travel over the network and can affect our file on the computer. 2.5 Unit Summary In this unit, the students are supposed to learn the basic concepts, types, advantages and disadvantages of network. You shall develop essential skills through the classroom learning, participation in activities and laboratory-based work in the unit. Computer networks help us have such services as emails, online newspapers, blogs, chats and other network services offered on the Internet. Therefore, understanding network will help students to become actors and beneficiaries of the networked society and share resources and have a faster communication. The following are the main points covered in the unit. A computer network is interconnection of two or more computers or any devices that able to connect over the network. 63 Unit 2 : Computer Network To make a communication and interconnection between devices on a computer network, networking hardware, also known as network equipment or computer networking devices, which are electronic devices, are required. These are end devices, intermediate devices, connection medium and protocol. End devices are the sender and the receiver which can be any devices capable of composing, sending and receiving a message. Intermediate devices are interconnecting devices that found between end devices, as their name indicates. Intermediary device includes network cards, routers or network switches, modems and Ethernet repeaters. Network interface card (NIC) is used to plug a UTP cable to the computer. It has wireless variety which allows a computer to connect to the network wirelessly. Repeaters, as the name indicates, repeat and boost the signal. It accepts weak signal on one port, illuminates the noise that makes signal week, regenerates signals and resends the boosted, cleared signal over the other port. It has an analog version, which is also called Amplifier. Amplifier amplifies not only the signal but also the noise and sends it again. Switch is more intelligent device than repeater because after learning the network, it forwards packet to the destined port or a device connected to the port only. A router is a device that connects different types of network and more intelligence than switch. Router uses routing tables. Router selects best path through networks. Protocol is a common set of rules to manage communication (packet transmission) through a network. Connection media used in networks are wired (guided) and wireless (unguided) media. UTP is the most common wired medium used in local area networks. 64 Grade 9 Information Technology Student’s Textbook Wireless media can be radio waves, microwaves and infra-red waves. Based on size, network can be classified as personalized area network (PAN), local area network (LAN), metropolitan area network (MAN) and wide area network (WAN). PAN is the smallest area network which can be made using Bluetooth network. LAN is larger than PAN and smaller than MAN in number of computers and geographical coverage. LAN can be a small office, one campus or school, network. MAN convers area of a city and can contain multiple LANs. WAN covers very large area such as the globe. Network topologies include bus, star, ring and mesh topologies. A bus topology is a cheap network where computers are connected to a common backbone cable. In a mesh topology, every computer in a network is connected to each other independently. Mesh topology needs more cable and more ports on the computer. In star topology, all computers are connected separately to a central device, which can be a switch. A failure of the central device results in a failure of the entire network. Ring topology looks like finger ring that connects devices in such a way that each device is connected to other two adjacent devices. Failure of one node in ring topology network will affect the whole network. Peer-to-peer and client-server networks are based on resource access and sharing. In peer-to-peer network, resources are distributed among peers and each peer can be a server and client at the same time. In client server, resources to be shared over the network are adminis- tered centrally and there is a dedicated server which provides resources called servers and there is also a dedicated client which requests a re- source from the server. 65 Unit 2 : Computer Network Network is advantageous in increasing communication speed, sharing data, sharing hardware, sharing software and getting entertainment. Network also disadvantageous in security concerns and incurring cost for setting up and administration of network, hardware, software and the like. 2.6 Unit Review Exercise Part I: Write whether the following statements are true or false. 1. Each individual client computer is responsible for the security of the resource in the client and server networks. 2. Software cannot be shared over the network. 3. A MAN is usually within the boundary of a private building. 4. In ring topology, each node is directly connected to many other adjacent neighbors. 5. WAN has fewer nodes than LAN. Part II: Choose the correct answer among the alternatives provided. 1. Which one of the following is different from others? A. Star B. Ring C. Bus D. Peer-to-peer 2. The term WAN stands for ____________. A. Wide Area Net B. Wide Access Network C. Wide Area Network D. Wide Access Net 3. If a given two networks use separate and different protocols, which one of the following devices can be used to link them? A. Repeater B. Router 66 Grade 9 Information Technolo

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