They should be not more than a page long. You may submit as many as one per class. To submit none is fine. These non-graded papers cannot count against you. They provide an opportunity for us to communicate beyond that which is available in class.
Any topic relating to class discussions, lectures or readings is appropriate.
Use this chance to make comments and ask questions as you wish, to try out a paper topic, to work through a reading, etc. . I read each one and return it with comments. I keep track of who does them. These are not required. From time to time I shall suggest in class that you do something in connection with a point being made in lecture.