Why I Hate "Take Your Child To Work Day".

The students have 34 days of classes (not including weekends/school days off) and we're nearing exams. Even with the kids that come to school, there's a lot I need to totally "redo/reteach" when the others return. The day turns into one giant fiasco trying to figure out who actually went with a parent to work and who just decided to take a personal day. Sigh. Why can't they have this day happen in the summer? :S