States: Wisconsin: Winnebago
Try contacting the Omro School District Office, 455 Fox Trl, Omro, WI 54963 (920)685-5666.
The school system has changed a lot in the last few years. Almost all the small country schools have been eliminated and new schools have been built to house everyone at one location.
I would contact soon as school is almost over and the offices could be empty for a while.
In regards to your K/20th location. In Oshkosh, WI 20th St runs west out of town toward Omro area. Once it passes the Oshkosh City and Town lines it turns into Cty Tk K and then would take on a different name once reaching the city of Omro (if it does)