Referring to students as numbers....

It’s not about effective privacy per se. You’re a public school teacher too so every email you send is a public document. If I use MJ in my email and a private citizen gets a copy of it they may or may not know I’m referring to Manda Jo but most times they would have to investigate further to know who MJ is* and so I can say that I did what I needed to do to protect the student’s identity.
*Then it is up to the school and FERPA to protect the student.

Does that include colleges? When I went to college, 35 years ago, when the professors would publish (by posting them outside their doors) grades for certain things, they would refer to the students by their school registration numbers.

Yes FERPA applies to post-secondary schools as well.

But it does provide meaningful protection to the school’s fourth point of contact. Any bureaucracy will see these sorts of practices pop up for the CYA value alone.

Even if you and I and everybody else knows who the student ‘really’ is, when the shit hits the fan and the school gets sued, they have to be able to go to the jury and say they followed the industry best practices.

Following “best practices” which are obviously negligent is not a good defence to a negligence action.

Is there a database issue as well? That is, Tristan Stephane Balthisar Guglielmo (MY REAL NAME) is a lot easier to mis-spell than TSBG, so it’s easier to enter/lookup data. I suppose you’d run into issues with multiple students with the same initials in the same grade; but the same applies to the ‘privacy’ coding–John Smith, Jane Stevens, and Juan Soto all in the fifth grade.

So write the school and bitch about it.

It’s not my policy, so I don’t really care if you agree with it or not.

When were these privacy laws passed that require all this stuff? I’m just curious, as there was no such practice like this back when I was in school, but I graduated in 2003.

The question asked in the OP is not whether you (or I) agree with the policy; it’s why the school would do this in the first place.

Other have suggested that maybe the school is doing this in order to protect the privacy of the student, either because they actually want to protect the privacy of the student or becauase they want to avoid liablity under laws which require the privacy of the student to be protected.

My point is that the initials + grade code that the school is using doesn’t look like anything that could be relied upon to achieve either of these goals; therefore this is probably not the school’s motivation, and we need to look further for an answer to the question raised in the OP.

Why not? You see an email referring to SC 69/420 how would you know it’s me?