6-8 > Technology
 Grade level: 6-8 Subject: Technology Duration: One class period
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Students will understand the following:
 1 A pebble calculator works in a way similar to an abacus.

For this lesson, you will need:
 • Abacus (optional) • Drawing materials, including large sheets of paper • Compasses (optional) • Pebbles or other items that can be used as markers

 1 Review with your students how to use an abacus, making sure they understand the abacus was developed in order to store and calculate decimal numbers (0 through 9). Students should appreciate that the abacus was an early ancestor of the computer. If possible, have on hand an abacus with which they can experiment. 2 Tell the class that a pebble calculator works similarly to an abacus. Let students know that they are going to construct and use their own pebble calculators. Students may work on their pebble calculators individually or with partners. 3 Instruct students to draw a series of four concentric circles (freehand or with the help of a compass) with nine dividing lines radiating from the center to the outermost circle. One of the lines should point straight up to the top of the outermost circle. (The nine lines represent the numerals 0 through 9.) 4 Explain that the innermost circle represents the 1s place, the next the 10s place, and so on. The fourth and outermost circle represents the 1,000s place. 5 Next, have each student place a pebble or other small marker at the intersection of the innermost circle and the line that goes from the center of the innermost circle to the top of the outermost circle. Explain that the pebble represents the number 1. 6 Moving clockwise, students can represent the number 2 by placing the pebble at the intersection of the innermost circle and the next line. If they continue moving the pebble clockwise, they will reach 9. 7 After reaching 9, students must move the pebble out to the intersection of the second circle with the line that points straight up. Now the pebble represents 10. 8 Students can represent 11 by leaving the pebble at 10 and placing another pebble in the 1 position. By moving the second pebble clockwise around the innermost circle, they can get to 19. 9 Still in the second circle, the next position, moving clockwise, represents 20, then 30, and so on. 10 Have students figure out for themselves how to continue, moving out toward the outermost circle. Give them increasingly larger numbers to represent on their pebble calculators. They can go up to 1,999. 11 Challenge students to figure out how to go beyond the 1000s place. Then challenge them to find out a way to use their pebble calculators for storing and calculating decimal numbers that represent a fraction of 1—for example, .1, .10, .001, and so on.

 Older students should need less guidance. Give them the basic idea, and have them work out for themselves how to represent numbers 1 through 1,999 and beyond. Then challenge them to figure out how to use their pebble calculators to add and subtract.

 1 In what ways have computers transformed our lives? 2 How did earlier contributions from other cultures figure into the development of the computer? 3 How did the invention of the transistor revolutionize computer design? 4 Who owns and manages the information on the Internet? 5 How will expanding digital technology change the Internet of the future? 6 Why do some people fear that intelligent computers could replace people?

 You can evaluate your students on their successful construction and use of pebble calculators using the following three-point rubric:  Three points:pebble calculator correctly constructed; student uses the pebble calculator to represent numbers correctly  Two points:pebble calculator correctly constructed; student represents some numbers incorrectly  One point:pebble calculator incorrectly constructed, and therefore, all numbers incorrectly represented You can ask your students to contribute to the assessment rubric by determining criteria for a correct pebble calculator: at least four concentric circles with nine straight lines radiating from the center of the innermost circle to the outermost circle.

 Computers in Our Lives: Become an Observer Instruct students to list each useful device they come across during the course of one day that depends on a computer (microprocessor chip) in order to work. (Remind students that anything that provides a digital display, such as the display on a digital clock, contains a microprocessor chip.) Students should organize their devices into categories based on their uses. Next, tell students that, the same day, they will generate a list including each useful item they see that does not contain a microprocessor chip. Students should organize these items, as well. After both lists are complete, have students consider the following questions: “Can you detect a pattern in your lists? Are there certain categories of devices that have not been designed or redesigned so as to operate with a microprocessor chip?” Computers in Our Lives: Become an Inventor Divide your class into groups, and have each group choose a useful item, such as a kitchen sink or hair drier, that does not contain a microprocessor chip. Instruct each group to brainstorm new tasks its chosen item could perform if a microprocessor chip could be installed. For example, would group members give the item a set of instructions and create an input device? In what ways would the item be improved? What would it look like? Have groups design their new-and-improved items, and encourage them to share their designs.

 How Computers Work Ron White, Ziff-Davis Press, 1995As senior editor of PC/Computing Magazine, White is renowned for the way he explains complex subject matter. This is the most highly recommended resource for young adults through adults for this subject matter. The New York Public Library Student's Desk Reference: "Computers" The New York Public Library and Stonesong Press, Inc., 1993Futuristic and present applications, timelines of computers' development, definitions, jargon, and illustrations of computer parts are all presented in a highly-readable and enjoyable format. Computers for Beginners Margaret Stephens and Rebecca Treays, Usborne Publishing, Ltd., 1995Despite cartoon-style illustrations, this resource offers sophisticated, detailed explanations regarding computer programs, essential hardware and software, and such accessories as mouse, scanners, and compact discs.

 The Spider's Apprentice--Tips on Searching the Web Find out how web search engines work and explore how people navigate the Internet. Create a scavenger hunt with groups of students using different search engines and compare results. Computer Aided Dispatch Media Information Center Up-to-the-minute information about potential and existing traffic tie-ups demonstrates how service groups such as the Highway Patrol are using computer technology. Alternative Keyboards & Accessories For grades 7-12 this site offers information on problems of keyboard design. Invite your students to develop physical exercises and new keyboard designs to help with the problems discussed at this site.

 Click on any of the vocabulary words below to hear them pronounced and used in a sentence. Definition:Constituting a very large number; innumerable. Context:This myriad of uses makes the very word computer seem inadequate, but stripped to its chips, that's all a computer is--an astonishingly fast calculator. Definition:Relating to or being a device in which data are represented by variable measurable physical quantities. Context:They call the wall clock an analog clock. Definition:Expressed in binary digits or bits (see below) for use by a computer. Context:A digital clock tells us that time jumps from one second to the next with nothing in between the numbers. Definition:A shortened form of "binary digit." It is the smallest unit of information a computer can understand, representing a "0" (off) or a "1" (on). Context:An electrical connection or signal is sent as bits along the wire to the ROM BIOS chip. Definition:A device that provides a way of communicating with a computer. Examples include mouse, keyboard, joystick, microphone, scanner, modem. Context:A computer needs a way to connect to the outside world: a keyboard and a mouse for input, a screen for output. Definition:A device that lets a computer communicate with you. Examples include a monitor, a printer, a set of speakers. Context:A computer needs a way to connect to the outside world: a keyboard and a mouse for input, a screen for output. Definition:Central Processing Unit. The computer's microprocessor chip, often referred to as the brains of the computer. Context:It [the computer] needs a brain, a central processing unit for basic operations like adding and subtracting. The CPU is the computer's main coordinator. Definition:Random Access Memory is a temporary storage for data which disappears when the computer is turned off. Context:Think of RAM as something written on the blackboard. When you are finished with the words, you just wipe them out. Definition:Read Only Memory is a permanent storage for data which is essential to the basic operations of the computer. Context:Think of ROM as letters carved in stone. Definition:Basic Input Output System is the part of the operating system that handles communication between the computer and all of its peripheral devices (keyboard, printer, mouse, etc.) usually encoded as ROM for protection. Context:Inside BIOS there's a prescribed table that matches voltage levels with letters and symbols and signs of binary code. Definition:Storage device usually installed inside the computer's case which holds software programs and data which the computer can retrieve when it needs them. Context:Thousands of instructions in a word processing program are loaded into RAM from some form of external device: either a removable floppy disk or a hard drive. Definition:A portable storage device which stores data in the same way that the hard disk does. Context:Thousands of instructions in a word processing program are loaded into RAM from some form of external device: either a removable floppy disk or a hard drive. Definition:A hand-held device that lets you point to and select items on the monitor screen. Context:This funny-looking device was the world's first mouse. Definition:A modulator-demodulator is a device that modulates (transforms) digital signals from a computer into the analog form that can then be successfully carried on a standard voice phone line) and demodulates (transforms the analog signals back to digital signals before passing them to the receiving computer). Context:What makes it all possible is a box that takes digital signals from the computer and turns them into analog signals that can travel on the phone line: a modulator-demodulator or MODEM. Definition:Being or seeming to be everywhere at the same time; omnipresent. Context:When people talk about online services, it's about really making this a ubiquitous service.