College football rankings, grades: Iowa, Ohio State earn 'A+' as Alabama gets 'C-' in Week 6 report card | CBS Sports Headlines College football rankings, grades: Iowa, Ohio State earn 'A+' as Alabama gets 'C-' in Week 6 report card A look at how the national championship contenders fared in … Continue reading College football rankings, grades: Iowa, Ohio State earn 'A+' as Alabama gets 'C-' in Week 6 report card