Hundreds of thousands of public-sector workers are on strike in England over proposed changes to their pensions. Several thousand of the striking workers marched on Parliament, blocking traffic. The teacher strike closed 40 percent of state schools in the country. Border Agency staff also walked out, threatening airport delays. The Metropolitan Police Commissioner says 90 percent of police staff who handle calls have not shown up for work, slowing police responses. Both the government and the opposition have condemned the strikes.