We have baseball class here in a lot of the schools (TX), so it is practice. They usually schedule it as the last class of the day so it just bleeds into the after school practice. After cuts, kids transfer out of the class. Older guys usually know where they stand before tryouts.
It is almost like college and walk on tryouts. The coaches pretty much know who is going to be on the team. The varsity kids who are in baseball class and returning pretty much don't try out. Coach runs a separate practice for them while new kids or kids who didn't make the team the previous year are going through tryouts.