EDITOR'S NOTE: Much has been made of the youth explosion on the PGA Tour in 2010, with players 30 or under winning nearly half of the events through August, including the last three majors. A similar phenomenon is happening on tour practice tees: Teachers in their 30s, even their 20s, are squeezing between the Butch Harmons and David Leadbetters. Here we recognize these young stars with a new list: Golf Digest's Best Young Teachers. But this is not just about teaching tour players; in fact, most of these men and women spend their days with golfers like you, at clubs and golf schools across the country--in 21 states, to be exact. To pick them, we started with our Top 20 Teachers Under 40, then we exhausted our industry contacts to find candidates to survey and interview. Finally, we settled on 40 great teachers under 40 (see ranking below).We begin with 36-year-old Sean Foley, who has been working with Tiger, and the rest follow in alphabetical order. Check them out, try their two-minute tips, and look for them in every issue.