ESC Units

As we come close to the end of another school year, I like to survey my students to get their reactions to the various units we covered in the Exploring Computer Science course.  Because of time constraints, various testing, assemblies, etc. I don't always have time to go through teach unit.  With some units, such as the data unit, I skim through them and sometimes even have to omit.  It would be interesting to hear what units you feel are the most important to cover and if you have any tips to share about how you manage the course curriculum.