Part of Unit: Operating Systems
Lesson Plan Overview / Details
When computers think, it must be very precise with definite numbers. However, much of the information we get from nature does not come in definite easily written numbers, like sounds or waves rolling. We call information is constantly changing “analog” because it is an “analogy” of a real-life situation, like a rolling wave. For computers, however, information must be “digital”, which comes from digit, or number.
- Computer Class
- 150 Minutes
California Career and Technical Education Standards
California Academic Content Standards (Reinforced)
Objectives and Goals
- At the end of this lesson, students will be able to explain the difference between analog and digital information.
- Students will be able to explain why computers need to process information in digital format.
Activities in this Lesson
- Opening Activity - Hooks / Set
When the students come into the room, the teacher should have pictures on the overhead projector, (perhaps a Powerpoint) of various music producing devices like an old-style gramophone, a cassette player, a CD player and an Ipod or mp3 player.
Ask the question: “What do all these things have in common?”
You probably will get various answers, but the answer we are looking for is that they all make music.
Point out the gramophone and ask “How does this one make music without electricity?”
Lead the class in a discussion of how the different devices work. Point out which ones are analog (the gramophone and the cassette player) and which are digital (the CD player and the mp3 player).
If you wish, bring in historical context of the development of the record player by Thomas Edison.
- Gramophone [ View Image ] [ Download Original ] Gramophone
- Cassette Player [ View Image ] [ Download Original ] null
- CD Player [ View Image ] [ Download Original ] null
- Paper Record Player [ View Image ] [ Download Original ] null
- MP3 Player [ View Image ] [ Download Original ] null
- Gramophone 2 [ View Image ] [ Download Original ] null
- Record Player [ View Image ] [ Download Original ] null
- Record CD Player? [ View Image ] [ Download Original ] null
- Lecture - Lecture
Explain the difference between analog and digital information.
Draw a sine wave on the board and point out its parts, the wavelength, amplitude, etc. Explain how a wave is created in nature.
Ask the students “Where would you find something in nature that creates a wave of this type?” Answers may include an ocean wave, a grandfather clock weight, a child on a swing or a weight bobbing on the end of a spring. Point out that sound is also a wave.
Draw a number scale by the wave you have drawn on the board so you can give the height of it a value. Point to the diagram of the wave and follow the curve as it goes up and down. Ask the students how high it is at a given point. Move a little bit up or down the wave and ask how high it is now. Point out to the students how hard it is to give a value to the height of the analog wave because it is constantly changing. Ask them how important it is for computers to have concrete; never changing numbers to work with.
To make an example, ask the students what it would be like if they had 2 million dollars in the bank and the bank computer changed the 2 to a 1 because the numbers were close! (Or change it to a zero!)
Ask students how the changing of one number in a computer program might affect the program, when the changing of one number could mean an entirely different computer command. (For example, an addition command could become a subtraction command)
Now explain how the best way for computers to make sure they have accurate information is to not depend on trying to guess how high a curve is. We use something that cannot be mistaken—whether the electricity is on or off. Unfortunately, this only gives us two pieces of information to work with, “on” or “off”. It turns out that if we think of “on” and “off” as the numbers “1” and “0”, there is a type of mathematics called “binary” that we can use to do computer calculations with.
- Demonstration - Demo / Modeling
When you start the lab, the teacher should have an old-style record player as a demonstration. A gramophone would be best, but probably too expensive. Any old turntable will do, with a player built out of a paper cone and a needle as demonstrated in this video:
Use the record player to demonstrate how you can create music without any electricity. Spin the record player, put the needle on the record and have them listen to the music coming out of the paper cone. Explain to them how the music is created by the needle wiggling back and forth in the record groove, which vibrates the paper and re-creates the sound that was used to originally make the groove. The groove is shaped like an “analogy” of the original music.
- Calm Down, It's Only Ones and Zeroes- How to make a Paper Record Player video [ Watch Video ] [ Download Original Video ] This is a video showing how to make a paper record player for the Calm Down, It's Only Ones and Zeroes" lab. From the web site: http://www.wonderhowto.com/how-to-make-your-own-homemade-record-player-175535/
- Lab Activity - Lab / Shop
A vinyl record
Masking tape/ scotch tape
Paper to make a cone
Arrange the students into groups of 2 or 3. Have each student take out a sheet of paper and start a lab write-up titled “11 Cheers for Digital! Lab Write-up” with their name and other information in the upper right corner.
Give each group a vinyl record, preferably a 78. (78 records are stronger and have deeper grooves, so they work better for this lab).
Have them take a pencil or wooden dowel and put it tightly into the hole in the middle of the record. If the pencil does not fit tightly, wrap a little masking tape around it until it does.
Give them a piece of paper and have them roll it into a pointed cone and tape it together. Tape a needle or pin into the point of the cone so it sticks out a half inch or so.
Have one student place the tip of the pencil on the table and rotate the record slowly. Then have another student hold the top edge of the cone loosely and drop the needle gently in the groove of the record until they can hear a sound. Have them try different speeds and directions until they can get passable music out of their “record player”.
On their lab sheets, have the students write a brief summary of how the paper “record player” works.
Ask the students how easy or difficult it would be to assign a number value to the music at any given point.
Now have the students return to their seats. As they are sitting in their seats, turn the lights off. Ask whether the light is off or on. Now turn the light back on and ask the same question. Repeat several times, and then ask if there was any question as to whether the light was on or off. Explain that this is how digital information works, and how computers need information in digital form so there will be no question what a certain number is.
Now have a student clap with a slow, steady beat. Turn the light off and on and have the students write a “1” or “0” on their paper for every clap, a “1” if the light is on and a “0” when the light is off at the clap. Stop the clapping and have them look at their paper. Tell them that this is what a computer sees- just a series of “1”s and “0”s.
Explain to the students how computers send information as “ square waves” where a “1” is a pulse of electricity and a “0” is no electricity. Draw and example of a square wave on the board. Have the students draw a square wave like a computer might see just below the line of ones and zeroes they just created.
Explain that this is how computers create information, by turning the electricity off and on, much like a light switch. This way, just like in the previous activity, the computer can be sure it has the right information. Since computers only use two numbers, “1”and “0” (off and on), we call this system of seeing information “binary”. “Bi” means two, like a bicycle has two wheels.
Have the students write in their own words on the lab write-up why having computers use only ones and zeroes keeps them from making mistakes with numbers.
- Closing Activity - Closure
Have the students research the words “analog” and “digital” on the internet and write a brief definition of each term on their lab write-up.
Have the students write a summary paragraph IN THEIR OWN WORDS on their lab write-up explaining the difference between analog and digital information as they understand it now.
- Assessment - Assessment
This assignment will be assessed by the teacher grading the lab write-up.