It often feels as if preschoolers remember everything, from the playdate they had with their best friend six months ago to the chocolate milk they reminded you to buy yesterday at the grocery store. "The reason that 4- and 5-year-olds remember more than adults do is that they're not yet able to discern what's important and what's not," says Carolyn Rovee-Collier, PhD, professor of psychology at Rutgers University in Piscataway, New Jersey, and a specialist in pediatric memory development. "As kids get older, they become more selective in what they learn and remember, which means that certain memories from early childhood will stay with them, while others won't." But how much of his preschool years will he remember when he's older? And more to the point, can you do anything to make all the wonderful times and special people stick in his head? Thankfully, yes. He just needs a little help from you to ensure these precious memories make the cut.