The OP is using GAFE, Google Apps for Education. It's basically the same as the commercial offering. Students don't create their own accounts, the district likely has a process in place that automatically provisions the new accounts using something like Google Apps Directory Sync or a 3rd party app that uses the Google Accounts APIs. Kids / employees go to sign in and it Just Works. (TM).
(Source: I've implemented GAFE / GADS at a K-12.)