A method for operating a computer network for example a school to preload the content of web addresses on the local memory, i.e. the web cache memory for use in for example a subsequent lesson. The network comprises at least one device, a web cache memory, and internet access apparatus to connect a device on the network to internet using a web browser, relevant devices on the network being accessible to a network administrator and defined network users (teachers and pupils), a method whereby one of said defined network users (teachers) uses a modified web browser to define a set of web addresses (web pages) to be accessed, said set of web addresses being stored in the network, and operates the network to cause the content of the set of web addresses to be stored on said web cache memory, whereby the content may be accessed by the pupils during said lesson via the network without further access to internet. Limits or quotas may be set up for the amount of memory space usable by each user so as to prevent overload of the memory and users may be limited to access web pages defined by one or more preload tasks on the memory at a particular time. Software to allow the method of the invention may be loaded on the web cache.