The Ohio Department of Education is changing the report-card ratings for 20 Columbus schools that had cheated their way to better grades. The state will lower the grades for most of the schools Wednesday when it issues changes to three years' worth of recalculated ratings for schools in the large district. Eighteen of the district's 116 schools will receive lower overall ratings for the 2010-11 school year. That's the school year that has been most scrutinized by investigators looking into the manipulation of attendance data by administrators trying to improve the school's overall rating. The state already has reissued 2010-11 report cards for a handful of other Ohio districts that also scrubbed data.