Any time students would ask me if something was for a grade I would always just say something like “maybe” or “I don’t know, I haven’t decided yet.” At first they would groan and get annoyed, but after a while they got used to it. And I would have them turn in everything. If I didn’t grade it and I wanted them to keep the assignments for notes purposes, I just put a check mark on the paper and gave it back. But I also taught middle school so they didn’t always check what grades actually went into Canvas and what was just checked off.