Give a child a tennis ball and he'll be entertained for a day; teach a child to play tennis and he'll become a star, get rich, and fund your retirement. Prepare for a well-financed future with today's Groupon: for $45, you get three semi-private kids' tennis lessons from Elf Tennis (a $105 value). This Groupon is valid at 11 locations in New York, Brooklyn, the Bronx, Hoboken, Southampton, West Hampton, and Water Mill.

Founded by former All-American Esther Forrester, Elf Tennis molds tennis tenderfoots into pintsize pros with a mobile training regimen that combines drills, age-appropriate games, and technical instruction. During the one-hour lessons, motivating coaches guide groups of four to six children ages 3–10 using themed games to grab their attention and teach tennis fundamentals such as the John Woo–inspired triple-racket backhand. In Alien Invasion, students get to run around the court when they make shots, and in the Restaurant Game, instructors call out fast-food orders corresponding to the kinds of shots the players have to use. To make tennis accessible and fun for young children, coaches lower the nets, serve larger, easy-to-hit balls, and wear cement shoes when playing one-on-one.