In 2006, the Swiss harmonica player Roland van Straaten landed in the Guinness Book of World Records for the “world’s largest music lesson"-a class of 539 at Camlog Biotechnologies Congress in Montreux, Switzerland. He might have remained on his perch if Steve Levitt, a Guitar 101 instructor at the Old Town School of Folk Music, hadn’t happened to organize a massive Chicago lesson in honor of the school’s jubilee year-and come across van Straaten’s entry. “The class was supposed to be a gift, a public lesson to Chicago in celebration of our 50th anniversary,” says Levitt. “The focus shifted a little after we realized we could also break a record.” The school hopes to lure 2,000 aspiring guitarists, and it has set aside August 7th in Welles Park for the attempt. The lesson is free but you need to register to be counted; to do so, go to oldtownschool.org or call 773-728-6000.