To provide a client server system and a recording medium suitable for teaching materials for school.

A CD-ROM recording a program and authentication information is prepared by a service provider 100 and provided to each school. The authentication information recorded in the CD-ROM is stored in a server 110 of the service provider 100. At each school 10, the provided CD-ROM is carried out in a computer connected to the server 110 through the Internet 50, and when the authentication information is collated, setting of a user ID is authorized. A security level is set for every set user ID, and the utilization range of the Internet is limited according to the security level.