To add an element of intrigue, you might suggest typing such a name backwards. This simple encryption technique can turn an otherwise ordinary telecommunications session into a top secret spy mission. Most youngsters will find the secrecy of passwords motivation enough to sustain their interest in telecommunications. Make a big deal out of having the password be private. Siblings need to be warned that they should not divulge each others passwords.
Tempers can flare plenty fast when such high level compromises of security occur.
Although in all honesty, passwords on most BBS's and national information services can be easily changed when the password is no longer secure. Most BBS's and information services actually recommend changing your password every few months - as an added security precaution. Showing children how to change their password is a worthwhile lesson in itself. But after the password is acquired, children need further coaxing and supervision. Ideally the child should communicate via modem with people they already know very well.