How was 'Screech' written into this show?

Well, it was bizarre. He showed up in the first episode of season 2 as Mr. B's administrative assistant. He was supposed to be on a work study placement or work experience from his university CALU but...

...he never returned! The closest he got to actually going back to university was during a school trip for 2 episodes in season 3. Mr.B also had to write an evaluation about Screech near the end of season 2, but that was it.

As the seasons progressed they made it apparent that he now worked at Bayside full time (discussing his wages, etc., and the fact he was there for five or six years) but they never even mentioned him graduating from CALU, so who knows? Either he dropped out of university and Mr.B took him on permanently, or he studied long-distance and graduated 'off-screen'.

In short: how was Screech written into this show? Very poorly. It was a rushjob, I think, to boost ratings after The College Years and TNC season 1 did poorly.

It may have been possible Screech had graduated college and had taken his first job back at Bayside as the assistant principal. Or it may have also been that he was majoring in education and had taken the job as Belding's assistant as a way to earn college credits. Although the first option is probably the more realistic.