When you hear the word "milestones," chances are you think of all the cute little triumphs you jotted down in your child's baby book: his first smile, his first wave, his first...everything. That journal may have been misplaced long ago (have you checked under the Wii?), but these accomplishments are more than just a memory. In fact, your kid's still making major strides. Some of these quantum leaps will make your life as a parent a lot easier -- others will only create a whole new set of challenges. But no matter what, your job's about to get more interesting. We're giving you a heads-up so you'll be ready!

5 TO 6 YEARS OLD

Playing group sports

Your child's not just getting stronger and more coordinated, he's also becoming more skillful at interacting within a group. "He's at a point where he can communicate well and follow directions most of the time," says Michael Wasserman, M.D., a pediatrician at Ochsner Medical Center in New Orleans. Plus, he's got a smidgen of patience and can take turns (usually). In other words, bring on the little soccer cleats!

As long as the parents on the sidelines don't behave like first-graders themselves and pressure the kids to win, group games are a great way to learn good sportsmanship, cooperation, and perseverance while getting some exercise. Just don't expect to see too much teamwork at first: "My five-year-old daughter, Eva, started T-ball this year, but I don't think the kids actually understood that they should work together to get more runs," says Erika Hanson of Fargo, ND. "Still, it's wonderful to watch a new, more organized level of playing together."