system
Given the following post, respond as if you're commenting on Reddit:
human
[Stranger Things] How did Suzie hack Dustin's grades?

How was she able to access the computer system of a small-town middle school from several states away, in the 1980's, if the internet wasn't released to the public until 1993? Even if she had access to ARPANET via military connections, how and why would the school be connected to it in that way?

Why did the school not have any record of the grades besides a single ASCII character in a computer system that would've been new technology at the time? No paper documents? Did the teachers not have their own records?
gpt
The school's computer had a modem connected to it for remote access.  It doesn't need to be part of the internet or ARPANET for that to be true.  Perhaps the local school district wants remote access, or even just the principle wants to be able to do some things from home.  It's cool technology after all, and we know they have at least one highly technical teacher working there. 

As for the single ascii character, they probably do have it on paper in other places, and teachers do have their own records, but you have to look at the intent and purpose of the hack.  

Dustin isn't trying to change his permanent record, he just wants the report card to look good when it gets to his house.  So hack the machine that prints the report cards.  If nobody ever brings it up, there's no reason for a teacher to even see the report card, let alone validate the accuracy of the grade that got printed.  In all likelihood this never gets caught because nobody has a reason to compare the paper records to the digital ones.