Large quantities

Lesson 5 : Large quantities

Representations: from clay to silicon

Computing

Sara Alade

Materials from the Teach Computing Curriculum created by the National Centre for Computing Education

Understand the meaning of bytes

Learn what the prefixes kilo-, mega-,
giga- and tera- mean

Practise converting between units

2

In this lesson you will:

2

We use nanometres to measure the
size of molecules.

We use centimetres to measure the
size of objects.

We use kilometres to measure the
distances between cities.

Why measure?

Why do we use different units?

Credit: The Galaxy (Chandra HST Spitzer): Wikipedia

Open Ended

Why do we use different units?

Using different measurement
units and prefixes …

● Not specific to computing
● Common scientific practice

Why measure?

4

Credit: Four Metric Instruments: Wikipedia

5

Bits and Bytes

Bits & Bytes

Do you know your speed and capacity?

• Know the difference between bytes and hertz

• Understand what capacity and speed measure in what components

• Know the correct size order of bytes and hertz to yotta

A byte is...

• ...made up of 8 bits

• ...the base unit of capacity

Multiple Choice

What is a processor measured in?

• Hertz

• Bytes

Processors

• ...are measured by how many millions of instructions they can carry out in one second

• so a 3Ghz processor can carry out three thousand million instructions per second

Multiple Choice

Hertz is a measurement of...

• capacity

• speed

Hertz measures...

• how many instructions are carried out per second

• how fast data can travel

Memory or RAM is...

• ... measured in bytes for capacity (how much data it can store

• ...measured in hertz for how fast it can transfer data between components

Multiple Choice

Storage has measurements in bytes and hertz

• True

• False

Storage is...

• ..measured in capacity for how much data it can store

• ...measured in hertz for how fast it can transfer data to memopryu

Bits & Bytes

Part 2: Working with large numbers

Working with large numbers

• Be able to write large numbers in digit and word form

• Know how to convert measurements into bytes

• Use standard form to represent large numbers

Multiple Choice

Is this component storage or memory?

• Storage

• Memory

Multiple Choice

Ryzen is a popular manufacturer of...

• RAM

• Hard drives

• Processors

• SSDs

Back to the big numbers

• How many bytes in a kilobyte?

• How many zeros does it have?

How many bytes in a ...?

• 1 kilobyte - 1,000

• 1 megabyte = 1,000,000

• Notice how many zeros

• Now finish the chart on OneNote - Bytes

• 10 minutes - come back at

Open Ended

What do you notice about the number of bytes in your chart?

3 minutes!!

Bits and bytes

Count the bytes in a couple of simple

problems.
Write the answers on your worksheet.

bits

bytes

÷8

⨉8

Bits, bytes, and prefixes
Unit conversions

bits

bytes

÷8

x 8

bit

b
binary digit
(0 or 1)

byte

B

8 binary digits

kilo

÷1000

mega

giga

tera

no prefix

÷1000

÷1000

÷1000

x 1000

x 1000

x 1000

x 1000

kilo-

K

thousands

mega-

M

millions

giga-

G

billions

tera-

T

trillions

What
does it
mean?

How
do I
convert?

What
does it
mean?

How
do I
convert?

Use these tables to translate:

200 bytes = 200 groups of 8 binary digits
1Mb = 1 Megabit = 1 million binary digits
10KB = 10 Kilobytes = 10 thousand groups of 8 bits

Use these graphs to convert between
units:

5GB = 5 ⨉ 1000MB = 5000MB
700MB = 700 ÷ 1000GB = 0.7GB
24Kb = 24 ÷ 8 KB = 3KB