The national high school graduation rate has slipped in recent years, despite an array of public and private efforts to boost the percentage of students going on to college, the Christian Science Monitor reports. But some districts are beating the odds, succeeding with many students who otherwise may have fallen through the cracks. The percent of students earning a standard diploma in four years shifted from 69.2 percent in 2006 to 68.8 percent in 2007, according to an analysis of the most recent data in “Diplomas Count 2010.” It was the second consecutive year of decline, says the report, which was released June 10 by Education Week and the Editorial Projects in Education (EPE) Research Center, a nonprofit in Bethesda, Md. That translates to 11,000 fewer graduates in 2007 than in 2006. At its peak in 1969, the national graduation rate was 77 percent…