Maybe I have one semi-smart idea. The way my DS is using his planner is pretty un-useful, because he just writes random nonsense on the day of class, instead of what he's actually supposed to accomplish. I think it would be good to write the assignments on the due dates in the correct space in the planner and then cross them off when they are turned in (not just completed, but submitted).
Does the school use some kind of "drop box" in the electronic submission process? You are supposed to be able to see if an assignment is submitted through our school's "Canvas" system, but not many teachers use this where we are.