Data Representation Lesson 2 Binary KS3 COMPUTING KS3 Computing

Lesson Aims 1 To understand how computers represent numbers in binary 2 To understand how letters are represented using binary 3 To understand how basic images are represented using binary

Humans use it because we have 10 fingers. Denary The denary number system (also known as decimal) uses 10 symbols (0-9) to represent numbers. It is a base-10 number system. Humans use it because we have 10 fingers.

Circuits Computers don’t have fingers, they have circuits. These circuits can be in one of two states, on or off. So they use a base-2 number system. On = 1 Off = 0

Binary The short name for Binary Digits is Bits Binary This number system is called: Binary The short name for Binary Digits is Bits

We need 5 volunteers to stand at the front facing the class. Binary to Denary We need 5 volunteers to stand at the front facing the class. Each place in a binary number has a value. These go up in multiples of 2. 16 8 4 2 1 Class activity: Work out the denary values of the binary numbers your teacher is displaying.

How do we represent these numbers in binary? Denary to Binary How do we represent these numbers in binary? 16 8 4 2 1 5 7 19 24 9 25 31 32

h 8 01000 i 9 01001 Representing Letters How can we represent letters on a computer? We can assign each letter a number h 8 01000 i 9 01001

Representing Letters a b c d e f g h i j k l m n o p q r s t u v w x y The whole alphabet looks like this: a b c d e f g h i j k l m 1 2 3 4 5 6 7 8 9 10 11 12 13 n o p q r s t u v w x y z 14 15 16 17 18 19 20 21 22 23 24 25 26 Complete the binary numbers and letters worksheet.

Picture Element  Pixel Representing Images How can we represent images on a computer? What is a pixel? What does pixel stand for? Picture Element  Pixel

How can we represent images on a computer? Representing Images How can we represent images on a computer? 1,0,0,0,1 1,1,1,1,0 1 = white 0 = black 1,0,0,0,0 0,1,1,1,0 0,1,1,1,0 1,0,0,0,0

White always comes first Representing Images 1,3,1 4,1 1,4 0,1,3,1 However, this can be simplified. 1,3,1 4,1 White always comes first 1,4 0,1,3,1 0,1,3,1 1,4 Using this technique, complete the Image Representation worksheet.

Write the answer to these questions in your book: Binary: Assessment Write the answer to these questions in your book: 1 Computers use binary, humans use what beginning with the letter ‘D’? [1] 2 Complete the sequence: ? 8 4 2 1 3 Complete the sequence: 128 64 ? 16 8 … 4 What does bits stand for? [1] 5 What is the number 17 in binary? [1] 6 What is the number 01010? [1] 7 What binary number represent the letter ‘E’? [1] 8 What binary number represent the letter ‘X’? [1] 9 Why do computers need to use binary? [1] 10 What is the number 101110? [1]

Complete the following work: Independent Study Complete the following work: ? PLANNER This work is due for next lesson.