There are several purposes for writing a reaction paper. One is to get points that will help you get a good grade in this class. Another is to prove to me that you have done the readings. Both of these are important, but most important is that it is a process of thinking out loud on paper that should help you to understand the readings better.
What I want
    There are several different ways to write a reaction paper. One is just a summary of the readings, which is not terribly demanding. Even on weeks where you don't put a whole lot into it you should always do that. Even at this level you should not be writing "the author said this, the author said that," but trying to summarize the argument  they are making or critiquing how they have done what they set out to do. If there are readings from more than one source how do they fit together or not fit together? What questions, if any, does this reading raise? You can also pick out a single theme in one or more of the readings that you are particularly interested in talking about. You might even pick out something minor in the readings that relates to something you have found in your research.
What you will get out of it
    A course like this is only 50% or so what happens in class. Most of what you will learn comes from you doing the reading and thinking about it. Your papers should help you focus your thinking. It is easy to have vague reactions in your head, but in order to write something you need to organize your thoughts. Your reactions also let me know what things you are interested in / puzzled by as I think about what we will do in class the next week. 
Technical stuff
    All reaction papers should be posted  the first day of the week and should cover the material for that week. No late papers will be accepted.