Your kid is getting notes from the kindergarten teacher for rule-breaking.
Transitions, transitions! From the carpet to the desks, the desks to the line, the line to lunch, lunch to recess, recess to rest time. Preschool likely didn't place all of these demands on your child, and adjusting to a highly structured day can often cause behavior trouble to crop up, says Robin Davis, a kindergarten teacher in San Francisco. Why? Kids live in the moment; if your child is happily building a masterpiece out of blocks during free play, he simply may not want to stop to line up for library.
No matter what, if your kid is being called out for rule-breaking, including aggressive behavior like hitting or back-talking, and refusing to mind those in charge, make an appointment to meet with his teacher -- even after just one red flag. After all, you may have stuff going on at your end (like a new sibling's arrival or a recent job loss) that could help her better understand the behavior issue. Together, you can also look for patterns and come up with a discipline plan. If, for example, your child tends to struggle at the end of art time, ask the teacher if she could give your son an extra personal cue to help him. ("Owen, you have just a few minutes left before cleanup.") Also find out what transition cues the teacher uses in class. If she claps her hands and says, "One, two, three, eyes on me," do the same thing at home to make it more familiar to your child, says Micucci. Finally, ask the teacher if she'd be willing to contribute to a sticker chart that you keep in your kid's backpack, Micucci suggests. For each day he follows the rules at school, he gets a sticker. At home, he can earn another for following the rules. This shows that behaving well is equally important at home and at school.