5.1 Networks
5.1.1 Why use networks?
5.1.2 Network types: LAN, WAN, PAN, and VPN
Types of network: PAN, WAN, LAN, and WLAN
Very clear diagrams and explanations of PAN, LAN, WLAN, and WAN. The diagrams are clear and include the location of key hardware such as switches, clients, and servers.The following pages also have good coverage of the other Computer Science networking topics, including network topologies.

LAN vs WAN
BBC Bitesize has a good overview of the differences between LANs and WANs, including some very clear diagrams. It does not cover Personal Area Networks (PAN) though. The very similar GCSE Computer Science page includes both a video and an explanation of WPAN and PAN.
Computer network types
Computer Network Types is a short but clear explanation of the main types of networks in Computer Science. It covers PAN, LAN, MAN, and WAN with very clear diagrams and explanations.
5.1.3 Wired and Wireless connectivity
Connecting to the Internet
The BBC's Connecting to the Internet does a good job of explaining the requirements for connecting to the Internet as well as the major media types (including, copper cable, fibre optic, ADSL, and 3/4G). The pages are very detailed and give advantages and disadvantages for each connection type.
Network cable types
About Tech has one of the better explanations of network cable types, covering the essentials including coaxial, twisted pair, and fibre optic. The hyperlink-studded text makes it easy to students to find out about any related terms or concepts which confuse them.
5.1.4 Network speeds
Global Internet speed
This excellent page from Akamai features interactive charts to help students visualise Internet trends. Students can view a global map of Internet speeds (which holds a few surprises) and customize the graphs to show data and changes from which countries and time periods they want. A great way of examining potential digital divides.
5.1.5 Network Protocols
Internet Protocols
The most common Internet protocols - TCP/IP, FTP, POP3, STMP, VOIP, and HTTP are given the BBC treatment in this page. Although largely text based, the resource clearly explains each term and uses examples to highlight how these protocols are used in everyday life, even if we don't notice them.
Packet attack game
In this simple game students must attempt to corrupt, kill, or delay data packets as they are sent across the screen. This game might now seem very educational at first, but on later levels (5 onwards) the data transmitted has additional features to detect corruption. For example, packets are sent with a sequence number (just like an IP packet), so delaying a packet no longer causes problems. This game can lead to some good classroom discussions about how network protocols prevent the problems shown in the game.

Network protocols
These four videos explain the main networking protocols that students are likely to encounter, from http and ftp to email protocols. Although designed mainly for the Edexcel GCSE Computer Science, they cover an appropriate level of detail for most courses.
5.1.6 Data packets
Circuit switching and packet switching
The Internet gives an overview of how the Internet works and also clearly explains the difference between circuit switching and packet switching.
Network parity interactive
This is an interactive version of the classic parity magic trick, which can also be performed with playing cards in from of a class (it generates a bit more enthusiasm when done live!). The activity is simple: set the parity bits correctly (the system uses even parity), then as the computer to randomly flip a bit. It should be possible to detect the change by examining the parity.
Video: There and Back Again: A Packet's Tale. How Does the Internet Work?
A really accessible overview of packet switching, using the example of accessing a web page. The steps are broken down and explained with real life examples, as a web page hosted in the US is fetched by a computer in the UK.
5.1.7 Network Topologies
Network Topologies
BBC Bitesize has clear revision materials for the three main network topologies: star network, bus network, and ring network. As always, their diagrams are very clear and easy to understand, and each topology has a clear table of its advantages and disadvantages.

Network topology videos
These four excellent videos from Computer Science tutor cover the four main types of network topology. Each video does a great job of showing the physical topology and discussing the advantages and disadvantages of each. The videos are relatively short - around 2 minutes - making them great revision / review tools.