1. Network Types & Speed Learning Objectives:
5.1.1 Understand why computers are connected in a network
5.1.2 Understand the different types of networks
5.1.3 Understand the network media
5.14 Understand that network data speeds are measured in bits per second

2. What is a Computer Network?
A network is a group of computers and other devices connected together.
As a class come up with a list of activities that computer networks make possible.
Activities:
Now complete tasks 1.1 and 1.2.

3. Types of Network
Computer networks are categorised according to their geographic coverage.
Type of Network
Description
Example
Wide Area Network (WAN)
Connect computers over a large area such as a town, city or country.
Company creating a private WAN to connect different parts of their business securely
Local Area Network (LAN)
Connect computers over a building or a site.
School network
Personal Area Network (PAN)
Connect the computers or devices used by one person.
Bluetooth headset connected to a mobile phone
Virtual Private Network (VPN)
User encryption and special ‘tunnelling’ network protocols to enable them to connect securely over the internet.
Company using a VPN to connect different parts of their business without having to build their own network infrastructure.
Now complete tasks 2.1 and 2.2.

4. Network Media
There are three main types of network media that are used to connect computers together in a network.
If possible pass round examples of cat5 and fibre optic cables.
Copper Cable
Fibre Optic Cable
Wireless
Now complete task 3 using internet research.

5. Time = size of file (bits) / network speed (bits)
Transmission Speed
Data transmission speeds are measured in bits per second (bps).
Data storage is measured in bytes (1 byte = 8 bits).
We use this formula to calculate how long it will take to transfer a file.
Time = size of file (bits) / network speed (bits)
Now complete tasks 4.1 and 4.2.

6. Example
In this example we are going to calculate how long it would take to transmit a 5 KB file over a network with a speed of 10 Mbps.
Step 1: convert the file size to bits
5 KB: 5 x 8 x 1024
Step 2: convert the speed to bps
10 Mbps: 10 x 1,000,000
Step 3: calculate the time
Time = file size / speed

7. Time = size of file (bits) / network speed (bits)
Practice
File size: 4 KB
Speed: 3 Mbps
File size: 2 KB
Speed: 2 Mbps
File size: 2 MB
Speed: 8 Mbps
Time = size of file (bits) / network speed (bits)
size x 8 x 1024
speed x 1,000,000
Now complete tasks 4.3 and 4.4.

8. Challenge
Develop a Python programme that takes a file size in KB and a network speed in Mbps and outputs the time it would take to transfer the file.