..New York has nine specialised high schools, of which eight admit students using the city’s Specialist High Schools Admissions Test (SHSAT). The education they offer rivals that of private schools that charge $40,000 a year. The high schools are free. The most popular, Stuyvesant, sends roughly 25% of its graduates to the Ivy League or other top colleges. The school’s unofficial mantra is “Sleep, study, socialise: pick two.” It admits 4% of test-takers, pickier than Harvard.New York’s Democratic mayor, Bill de Blasio thinks the SHSAT favours parents who can afford tutors. He wants to “broaden” (ie, relax) the admissions criteria,...