What had been one of the lowest-performing, under-enrolled schools in San Francisco was little more than a pile of rubble as workers demolished Willie Brown Jr. Academy in the city's Bayview neighborhood. Loud hydraulic excavators bit off pieces of the few remaining walls still standing last week at the school, which served about 160 students in grades four through eight until June 2011. With blue sky visible above and gaping holes nearby, a paper sign directed visitors to the now-nonexistent counseling office. Soon, the tons of mangled rebar and concrete chunks will be carted off for recycling and the 4-acre...