The laid-back atmosphere of Boston Symphony Orchestra’s summer home can make it a great place to introduce even young kids to the joys of classical music. As listeners spread out their blankets on the lawn, they don’t have to worry about the kids fidgeting in the seats or blocking the view of the adult behind them while they listen to the music. (As a bonus, kids under 17 attend for free.) The best performances for kids are the famous Boston Pops concerts, which feature a mix of crowd-pleasing classical fare and contemporary numbers, including the annual Film Night when composer John Williams conducts favorite movie themes. The BSO also offers special programs for kids on Sunday afternoons when volunteers lead arts-and-crafts projects before the show and explain the instruments and themes of the music to deepen their appreciation of what they hear.