A school board in Colorado is so desperate for revenue that it is selling advertising space on the report cards that students at 91 elementary schools take home, the Washington Post reports. Jefferson County Public Schools has sold about $90,000 worth of two-inch ads over three years from an arm of the state government called Collegeinvest, according to 9 News in Colorado. Collegeinvest administers college savings programs and is interested in a captive audience — parents of elementary school students…