Every year pedestrians in downtown Chicago get an earful, as fighter jets maneuver against the backdrop of the blue sky above city skyscrapers, on their way to North Avenue Beach. It’s the practice run for the Air and Water Show. The Blue Angels dazzled people on Michigan Avenue as well as spectators at the beach on Thursday. They’re so impressive that one group of teens thought it was the actual show. The 56th annual show runs this Saturday and Sunday from 10 a.m. to 3 p.m. along the lakefront from Fullerton to Oak Street Beach.