Using a survey composed of a serious of questions about the course content at the beginning of the course can be a valuable instructional planning aid.  By knowing the knowledge and/or skill sets that the students are bringing into the course you will be able to "customize" you instruction to more accurately target their learning.  Content serveys can give a picture of the understanding your students have about the course you teach and how they are going to fit within that course.  Also, it lets you see their communication abilities, another valuable insight to have as you plan the selection of projects for the course.  The responses given by students can be helpful as conversation starters as you get them settled into the course.   By showing the class the results of their responses they can get a picture of themselves and their classmates.  All this information is valuable to the establishment of course that is based upon prerequisite knowledge and how much of this knowledge the students are bringing into the class.