Instruction Guide: Digital Information
This lesson delves into Digital Information; both how and why computers do everything with 1's and 0's. Students learn how numbers, text pictures, video and sound can be represented in a binary system. Equally important, students will learn why computers use the this cumbersome binary system (this is covered in the seond Demo: Human Computer).
 Review the Digital Information Worksheet worksheet with students before watching the Intel video: "Digital Information".
 Have student take notes during video

Note: some answers on the worksheet come from the subsequent PowerPoint presentation and discussion
Digital Information Lesson (see Digital Information PPT file)
Slide 1
Students should recognize the number as "one thousand and eleven".
 Remind student the comma is only there for "readability", is does not change the value of the number
Review the concept of "Place Value"
 We understand this number to be "one thousand and eleven" since it has one "thousand", one "ten" and one "one"
 We add these together to come up with 1,011; "one thousand and eleven"
 Technically, the digits "1011" should be written with a subscript of "10" at the end (1011_{10}), to indicated these digits represent place values in the decimal number system
 This is because there is a factor of 10 between each of the columns in the place value chart for the decimal (or base 10) number system

Remind student "dec = 10" and ask for other examples (decade, decathlon, etc.)
 Since the decimal (base 10) number system is the default system for us (what everybody assumes, unless you specify otherwise), in our society, we drop the "10" subscript and assume we are talking in base 10 unless otherwise indicated.
 This is why the decimal number system is called "Base 10"
Slide 2
Students may recognize this as a binary (or base 2) number
 This means the columns in the Place Value Table increase by a factor of 2
 In this Place Value Table, 1011 now means one "eight", one "two" and one "one"
 When we add these up we get eleven in the decimal (or base 10) number system

This is called the binary number system
 Remind students "bi = 2" and ask for examples (bicycle, biathlon, etc.)
 This is why the binary number system is called "Base 2"
Slide 3
The Binary Table lists decimal numbers in the leftmost column, how these map to the binary place values in the center columns, and the binary equivalents in the rightmost column.

Have students complete the table
 This can be done rowbyrow to find the digits
 This can also be done much quicker by observing the pattern that develops in the columns  in the 1's column the entries switch between 0 and 1 every row, in the 2's columns they switch every 2 rows, in the 4;s column they switch every 4 rows...... The table can be completed quicker by filling it out columnbycolumn.

Note that the center four columns are identical for the first and last rows.

Ask students what would need to be done to represent the decimal number 16 in binary?
 We need to add another column on the left; the "16's" column.
 Extend this idea with student to realize that any arbitrarily large number can be represented in binary, just by adding columns to the left  just like we do in the decimal number system.

Ask students what would need to be done to represent the decimal number 16 in binary?
 Key Point  any number can be represented in 1's and 0's
Slide 4
This slide shows a portion of the ASCII Table (American Standard Code for Information Interchange) referenced in the video.
 The ASCII code translates characters on the keyboard (text) into binary numbers

Each keyboard character is represented by eight bits, or one byte
 Remind students that a bit is a single binary digit (a "1" or a "0")

Ask students why the ASCII didn't use a nibble (4 bits) instead of a byte (8 bits) to represent text?
 4 bits give only 16 possible combinations (2^{4}) and they are more than 16 characters on the keyboard
 8 bits give 256 possible combinations (2^{8}, more than enough to cover all the characters on the keyboard)

Have students see if they can discern a pattern between the upper case letter ASCII codes and the corresponding lower case letter code
 In each case, the upper case letter and lower case letter are identical except for the third bit from the left  it is always a 0 for uppercase and a 1 for lowercase.
 When students press the "Shift" key, they are changing this single bit to a 0 from 1 for every letter they type.
Slide 5
This slide demonstrates that when a student types "CAT" into their computer, from the instant after their keystrokes, what the computer actually sees are twenty four 1's and 0's.

All the computer works with is these twenty four 1's and 0's, whether:
 Loaded into the RAM
 "Processed" by the Processor
 Saved to the Hard Drive
 Copied to a USB Flash "Drive"
 Uploaded on the internet, etc.

These twenty four 1's and 0's are only convert back to "CAT" the instant before they are seen by a human:
 Displayed

Output from a printer, etc.
 Key Point  any text can be represented in 1's and 0's
Slide 6
Digital pictures are made up of individual picture elements, or pixels
 Ask students if they have ever zoomed in "too far" to an image that looked OK when small on the screen, but eventually becomes boxy or blurred

A bitmap can be made of any image at any resolution.

Resolution is the of pixels in the picture, usually given as "X"x"Y"
 A 100x100 image would have 10,000 pixels
 Ask students how many pixels are in a typical computer monitor (1024x768)?

For a black and white image, the bitmap only stores one bit for every pixels
 Each pixel is either on or off

For color images, the bitmap must store multiple bits for every pixel
 For RGB, the bitmap stores how much Red, Green and Blue is present in each pixel with multiple bits (as binary values).

Resolution is the of pixels in the picture, usually given as "X"x"Y"
 Key Point  any picture can be represented in 1's and 0's
Slide 7
TBD  Video  same concept as digital picture, except rather than being recorded once, the image is recorded multiple times per second to create motion (like a stick animation in a flipbook). This is why video files are so large  they have to store hundred of digital pictures for every minute of video.
 Key Point  any video can be represented in 1's and 0's
Slide 8
TBD  Sound  our ears respond to vibrations (compressions) in the air. A speaker reproduces sound by compressing air (look at a woofer with the cover off  you can see it moving). The signal that controls the speakers movement can be translated into binary numbers.
 Key Point  any sound can be represented in 1's and 0's
Note: the companion website for the Intel video (linked as a Supplemental Instructional Material) contains recaps, animations and interactive activities for this lesson.
Digital Information Classroom Demos
Human Binary Counter
This demo give students a kinesthetic opportunity to understand binary numbers.
 Have a one student be timekeeper
 Have four students seated in chairs facing the class
 Identify the four chairs (from the right) as the 1's chair, 2's chair, 4's chair and 8's chair
 When a student is seated, that bit is a "0" and when they stand it is a "1"

Starting with all students seated (0000_{2}) have the students count up to 15 (1111_{2}).
 Call out the next number in the sequence, and once the right combination of sitting/standing is reached, call out the next number
 Time multiple teams to see which is the fastest Human Binary Counter
Human Computer (or "WHY computers use only 1's and 0's")
This demo demonstrates for students why computer use the cumbersome binary system for everything they do.
Supplies
 Print out all 3 pages of the Digital Info Human Computer Flashcards PowerPoint file on card stock.
 You will also need some sort of "blind"  a large box or barrier you can move your hands behind without being seen.
Supply Preparation
 Cut out each of the 12 rectangles separately.
 For page 1, on the back of the two white rectangles write "0" and on the back of one black rectangles write "1" and the other write "9"
 For pages 2 and 3, on the back of each of the 8 gray rectangles, label them "1" through "8" ordered by their increasingly darker shades of gray.
Student Preparation

The players:
 Select one student to be timekeeper
 Select one student to be the counter
 Select 8 students to be the RAM chips
 The teacher will be the processor

The Human Computer
 In a real computer, the processor and RAM chips communicate information through electrical pathways called a bus
 In the Human Computer, the processor (teacher) and RAM chips (students) are going to communicate visually and audibly
 When a processor sends information to RAM all the RAM chips must receive it correctly and at the same time.

In this Demo, the processor (teacher) is going to raise a card above the blind and the 8 RAM chips (students) are all going to call out simultaneously what that information is:
 All students must clearly/loudly call out the same thing
 All students must clearly/loudly call out at the same time
 RAM chips cannot talk to each other, so neither can students (no consultation  just call 'em like you see 'em)
 When the processorknows that the communication was successful, the next piece of information will be immediately shown
 The counter will keep track of how many pieces of information have been transferred and the timekeeper will record how long it takes to transfer 20 pieces of information.
Running the Demo

Ask students why computers use binary information since:

Binary numbers are much "larger" than decimal number
 999_{10} is only three digits in decimal, but it is ten digits (1111100111_{2}) in binary
 This requires more space and memory (expensive)

ASCII uses eight digits to store one character
 "CAT" requires twenty four 1's and 0's
 Again, this required more space and memory (expensive)

Computers has to translate back and forth so they can communicate with humans
 This conversion takes time

Binary numbers are much "larger" than decimal number

To begin the Demo, start with Binary Information
 Arrange the 8 students on the other side of the blind from you.
 From below the blind, raise the white rectangle and tell the students this is a "0". Have all the students call out "0" together.
 Repeat the above, using the black rectangle and calling out a"1".

Randomly raise the white or black cards a few time and have the students give chorus responses until everyone has the idea of how this is going to work.
 Do not lower the card and move to another if any student misidentifies the card, fails to call out, or is out of sync with the others
 When you are ready to begin, ask the timekeeper to begin timing when you hold up the next card, and ask the counter to say "stop" to the timekeeper when 20 cards have been called out successfully.

Using the binary cards, student can usually do about one card per second and are quite impressed with themselves.

Announce that you are going to repeat the Demo now with the decimal number system
 Quickly show the students the 10 gray scale cards, identifying each shade of gray by number
 Immediately restart the Demo and hold up a midrange card (4 to 6)
 Again, do not lower the card and move to another if any student misidentifies the card, fails to call out, or is out of sync with the others. Allow no consultation between the "RAM chips"
 Students generally do not get past the first card

Stop the Demo when you think they have got the point

Ask students to share why the decimal number Demo was so much harder
 The numbers all looked the same
 They had nothing to compare them to
 Some of RAM chips agreed, but others did not
 They had to resort to guessing, etc.

Ask students why the binary number Demo was so much easier
 The cards were distinctly different
 Everyone got the same results, right away
 There was no indecision
 They could move at a fast, rhythmic pace, etc.

Ask students again why they think computers use binary information
 They can go really fast
 It is easy and quick to distinguish between on and off (or two other extremes)
 There is less chance of one part making a mistake

Point out to students they were only using the decimal number system. Ask them how things would have been different if we had used ASCII, and they had to distinguish between 256 shades of gray

Try to coax out the point that it is much faster and far more reliable for a computer to send eight 1's and 0's than it would be for it to distinguish one single ACSII code value from the other 255.

Try to coax out the point that it is much faster and far more reliable for a computer to send eight 1's and 0's than it would be for it to distinguish one single ACSII code value from the other 255.
 Key Point  Computers can process binary information so much faster than any other kind, that is worth all the time, trouble and size to convert everything to binary
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