Columbia University's National Center for Children in Poverty has a terrific overview of the early childhood policies that research has found to be most effective in narrowing the achievement gap between poor children and their more affluent peers. One crucial element, the center's report says, is what it calls an "intentional curriculum."

The report defines this as a curriculum that is:

content driven, research-based, emphasizes active engagement with children, includes attention to social and regulatory skills, and is responsive to cultural diversity and children just learning English. An intentional curriculum is directive without using drill and kill strategies; it is fun for young children and promotes positive peer and teacher interactions. An intentional curriculum is developmentally appropriate.

Whole report gives a very concise helpful overview of the research on this crucial question. Good one-stop shopping for the press.