The expected answer here has something to do with "paperwork." One informal survey of K-12 educators in three Midwestern school districts showed "paperwork" consistently held the bottom rung on the "Best Part of Teaching" surveys. So you probably can't go wrong joining the crowd on this one. Unless, you want to stand out from the crowd.
Discussions with a number of newer teachers revealed what they really disliked the most about teaching involved parent contacts. Parent Conference Night was often a lowlight. Making calls to parents informing them of their child's misbehavior or missing work was also right down there. If this is true in your case, one way to handle it might include a statement like this: "One of the hardest things I've had to do is in the area of parent contact. I know much can be gained from talking with parents, whether in a formal conference setting or a simple evening phone call update. In order to improve I've set a goal to make at least ___ calls per week to parents to keep them current on how their sons and daughters are doing."