There are blue Googles and green Googles. The blue Googles and green Googles can't talk to each other. This is why you need to use only your school website number to sign into BCC when you're on the blue Googles but you should use your AOL website number to sign in when you're on the green Googles.
Technical support in non-technical markets often involves very interesting forensic reconstruction of customer mental models.
Seriously though, "forensic reconstruction of customer mental models" sounds like a blog post I'd love reading, especially if it were an ongoing series.
There is a BCC site on both Googles, but because Googles are physically separate, they must be copies of each other, like how Word at home is a copy of Word at school. If you save docs in one, they don't show up at the other. So you need one login for the blue Google BCC and one for the green Google BCC. Duh. You use your website number as a login name. It is like a telephone number: it lets you contact people, except instead of ringing their phone your message shows up on their website.
I am hoping that the "website number" is not the http adresse, but the number they have to dial to connect to the internet (yes dial like it was 1995 and you could still go on a plane with a bottle of water) because it would be disturbing if the teachers called "www.bingocardcreater.com" a "website number".
I'd also saw Patrick is talking about 2 different browsers on the same computer. "don't talk to each other" probably means they don't share cookies. If the user logs into one website with one browser, then the other browser doesn't become aware of each other. Clearly the 2 browsers don't talk to each other.