Why they do it: This is a frustrating age for kids; they have the vocabulary to express themselves but when something is bugging them they can't always spit out the words fast enough or with sufficient detail to get their point across. So when your preschooler doesn't want to share a toy but can't articuate that before it's snatched away, he may resort to hitting.
How to deal: If your child bops his pal over the head when he takes his Lightning McQueen car away from him, let him know that hitting is not okay and teach him how to use his words to fix the problem. "It's empowering for kids to learn how to negotiate for themselves," says Dr. Berman. Say, "It looks like you weren't done with your race. How about asking Peter if you can have the car back?" Some kids this age will still resort to biting when they're unable to cope verbally. If you have a snapper, use the same strategy to help him chill out on the chomping.
Why they do it: Preschoolers want to be in charge, and they also have a strong sense of how they like things to be. Sometimes your child may be making demands to see what she can get away with, and other times she just wants to let you know that you put her toothbrush away on the wrong shelf.
How to deal: There's a fine line when it comes to bossiness; you want to respect your child's wants and needs without becoming her puppet. If she tells you that only Daddy can pour her cereal, and your husband is nearby, it won't hurt to let her get her way. But if she orders you to give her another cookie, don't give in to her demands. Stop the sass by explaining that extra Oreos are only doled out if they are asked for politely. And if she insists on being snarky? Move on. Eventually the lessons will sink in, but for now you've got to pick your battles.
Originally published in the October 2010 issue of Parents magazine.