More Differentiation Goodness

In an earlier post I shared a literal Choice Menu that I am using in my Biology classes, a menu those classes started working with yesterday and that they are really enjoying.  I am also differentiating in my AP Environmental Science classes at the moment in a slightly different manner, this time by using a Choice Board.  In this Choice Board, students must choose an activity per row.  Each row's activities are designed to see if they understand a certain set of objectives (which you can find on this page), and each activity in the row is geared toward a different product/learning style.  Before being given this board, students read about the objectives, highlighting the "answers" to the objectives in the reading. 
Students are given deadlines when they are to have activities completed.  I normally don't do that - if this weren't an AP class, I would let this be much more student-directed in terms of pacing.  However, since AP classes are slaves to the test deadline (and APES is the first test on the first day of AP testing), I have to give them firm deadlines, unfortunately.  I get a little riled up about this, because I think it assumes that increased rigor equals "more stuff faster," which, in my opinion, isn't what true rigor is at all.  
I believe a part of true rigor is challenging students with respectful choices-hence the Choice Board above.  If you'd like to access this as a Google Doc, you can click here.  If you have any comments to help me make this better, please fire away in the comments below.