Teachers give Dallas ISD's new grading rules an F 12:00 AM CDT on Friday, August 15, 2008 By KENT FISCHER / The Dallas Morning News / The Dallas Morning News Tawnell D. Hobbs, Stella M. Chávez and Karin Shaw Anderson contributed to this report. Dallas public school students who flunk tests, blow off homework and miss assignment deadlines can make up the work without penalty, under new rules that have angered many teachers. The new rules will be distributed when teachers return to their campuses next week. But many who have already seen the regulations say they are too lenient...