These days one of the fastest-growing markets for after-school tutors is preschoolers and kindergartners, whose parents are hoping that if their kids learn to read before first grade, it will ultimately help them get into college and get good jobs.

 

Says the study's lead author, Greg Duncan, a social-policy expert at Northwestern University: "The kind of skills that matter in affecting later learning are things parents can pretty easily convey to their children in the home."

These include such basics as the knowledge of letters and the order of numbers.