Teaching Computing at KS3 Session 2

1 / 23

# Teaching Computing at KS3 Session 2 - PowerPoint PPT Presentation

Teaching Computing at KS3 Session 2. Sue Sentance and Sophie Baker Sue.sentance@anglia.ac.uk. From the CAS curriculum. KEY STAGE 2 Introduction to binary representation [representing names, objects or ideas as sequences of 0s and 1s].

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Teaching Computing at KS3 Session 2' - cicily

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Teaching Computing at KS3Session 2

Sue Sentance and Sophie Baker

Sue.sentance@anglia.ac.uk

From the CAS curriculum
• KEY STAGE 2

Introduction to binary representation [representing names, objects or ideas as sequences of 0s and 1s].

• KEY STAGE 3Introduction to binary manipulation. Representations ofunsigned integers
Today’s session

5:00 – 6:00 Binary numbers – converting between denary and binary

6.00 – 7.00 Programming in Scratch

Storing Binary Numbers

Inside the computer eachbinarydigit is stored in a unit called a bit.

A series of 8 bits is called a byte.

A bit can take the values 0 and 1

What is meant by?

1 byte ?

1 nibble ?

1 kilobyte ?

1 megabyte ?

1 gigabyte ?

1 terabyte ?

Storing data

1 byte

1 nibble

1 kilobyte

1 megabyte

1 gigabyte

1 terabyte

1 byte = 8 bits

1 nibble = 4 bits

1 kilobyte = 1024 bytes = 2 10 bytes

1 megabyte = 2 20 bytes = 210 kilobytes

1 gigabyte = 2 30 bytes = 210megabytes

1 terabyte = 2 40bytes = 2 10 gigabytes

Learning binary numbers

Converting binary to denary

Converting denary to binary

Base 10 (Denary)

10 different symbols to represent values:0 1 2 3 4 5 6 7 8 9

Values greater than 9 are represented using the place value convention:100s 10s 1s 3 5 7= 3x100 + 5x10 + 7x1ie. Three hundred and fifty seven

Base 2 (Binary)

2 different symbols to represent values:0 1

Values greater than 1 are represented using the place value convention:8s 4s 2s 1s 1 1 0 1

= 1x8 + 1x4 + 0x2 + 1x1=Thirteen

Number Bases

1

2

100

8

10

1

4

0

1

1

1

3

5

7

How to convert Binary Numbers to denary

Place values

8+ 0+ 2 + 0 = 10

in Denary

8

4

2

1

1

0

1

0

How to convert Binary Numbers to denary

128+0+0+16+8+ 0+ 2 +1 = 155

in Denary

Place values

128

64

32

16

8

4

2

1

0

0

0

1

1

0

1

1

Converting binary to denary

Convert the binary number 1011 0111 into denary:

128 64 32 16 8 4 2 1 1 0 1 1 0 1 1 1

=128+32+16+4+2+1=183

Conversion Exercise

Convert the following binary numbers into denary:

0 0 1 0 1 0 1 0 0 0 1 0 0 1

1 0 1 1 1 0 1 0 1 0 1 1 1 1

1 1 0 0 1 0 1 0 1 1 0 1 1 1 1 1 1 1 1

Conversion Exercise

Convert the following binary numbers into denary:

0 0 1 0 1 0 1 0 0 0 1 0 0 1

1 0 1 1 1 0 1 0 1 0 1 1 1 1

1 1 0 0 1 0 1 0 1 1 0 1 1 1 1 1 1 1 1

1

2

9

4

15

6

10

5

12

31

23

21

Teaching binary

Holding cards up activity

Finger binary

Cisco binary game

CS Unplugged actitivies

Converting Denary to Binary
• Write down the column headings for the binary number:64 32 16 8 4 2 1
• Process each column from left to right.
• If the denary number to be translated is greater than or equal to the column heading, place a 1 in the column and subtract the value of the column from the denary value.
• If the denary value is smaller than the column heading, place a 0 in the column.
Example

Convert 27:

27 < 64, so 0 into 64-column

27 < 32, so 0 into 32-column

27 > 16, so 1 into 16-column, new value = 27 – 16 = 11

11 > 8, so 1 into 8-column, new value = 11 – 8 = 3

3 < 4, so 0 into 4-column

3 > 2, so 1 into 2-column, new value = 3 – 2 = 1

1 = 1, so 1 into 1-column

64 32 16 8 4 2 1

0

0

1

1

0

1

1

Storing Numbers - Binary

EXAMPLE

Convert the denary number 227 into binary:

128 64 32 16 8 4 2 1

11 1 0 0 011

Convert to Binary

3 5 8 7

11 16 32 21

14 17 48 255

Convert to Binary

3 5 8 7

11 16 32 21

14 17 48 255

0111

11

101

1000

10000

100000

10101

1011

110000

11111111

10001

1110

Summary – why teach binary?

Binary is a set of instructions used to control the computer, and works with 1s and 0s

The computer understands them as on or off signals.

If the decimal system were used, there would need to be 10 different voltages, in which case there'd be more room for error with resistors etc., and therefore more room for corruption of data.

Today, the elementary building block for all modern computer systems is the transistor. A transistor is simply a switch, much like the light switch mentioned earlier.

A transistor can be in an off state, which does not allow electricity to flow, or in an on state, in which electricity can pass unimpeded. A transistor is a solid-state device that has no mechanical or moving parts. The switching of a transistor from the off state to the on state, or vice versa, is done electronically rather than mechanically. This allows it to be fast as well as extremely small.

So learning binary helps students to understand how a computer works