Quitting to go to school is NEVER "good cause connected with the work." It's treated as "good personal cause" and is disqualifying.
Your employer would have been within their rights to "lay you off" at your request and tell that story to UI, and it would be treated as a quit, and you'd have been out of a job with no UI. They did you a favor by keeping you on. Don't get cute next time, or it might not turn out so well.

