To whom would you target this type and level of curriculum? I can't possibly imagine anyone who has no intermediate to advanced programming experience being able to grasp your first assignment.
I am taking an intermediate java class, and what you are describing is some pretty complex stuff. Writing an interface as the second assignment? Sure, if the sttudents are at least second year computer science majors.
Besides, a lot of java is procedural (loops, conditionals, etc). So, prodedural principles are inherently part of the OOP process.
Perhaps I am not understanding the target student population, or I am underestimating the abilities of others, but the level of material you are suggesting is months away from a Programming 101 course. I think you would have a class full of confused students.