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.
This kinesthetic activity involves students acting out various parts of the Internet including websites, routers, servers, and clients. It starts by examining swtiching networks (e.g. telephone systems) before looking at routing networks such as the Internet.
This is quite a complex activity which requires some preparation and setting up, but when this is done it is an excellent way to help students understand these topics. Thorough instructions are given in three blog posts linked from the CSE4K12 page. It is also possible to vary the difficulty level by including fewer aspects, making it suitable for students of different age groups.
This activity was created for Computer Science & Engineering for K-12 by Gary Kacmarcik, and is licensed as Creative Commons Attribution-Share Alike.
Greg's Cable Map is an excellent site with an interactive map showing the location of major Internet backbones across the world. This is a great resource for helping students visualise just how Internet routing works.
The Internet gives an overview of how the Internet works and also clearly explains the difference between circuit switching and packet switching.
This smart-looking Prezi presentation by Phil Bagge is packed full of great graphics and makes a really use introduction to the Internet topic. It takes a clear and visual approach to the idea of a 'network of networks', and really helps students see the structure of the Internet.
This 12 minute video gives a rapid overview of computer networks. Despite its short running time, a lot of topics are covered, including MAC addresses, ethernet cables, and networking hardware. Some of the concepts (e.g. collisions) may not be relevant to all Computer Science courses, but their explanations are often linked to other related concepts (for example, collisions is linked to bandwidth which in turn is linked to switches).
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.
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.