Alberto Carvalho, superintendent of the Los Angeles Unified School District, was placed on leave on Friday after F.B.I. agents raided his home and district office this week. The Los Angeles Unified School District placed its superintendent, Alberto Carvalho, on paid administrative leave Friday, two days after the F.B.I. raided his home and his office, throwing the nation’s second-largest school district into turmoil. The... [1573 chars]