A University of Northern Iowa professor says the U-S may’ve turned the corner in efforts to prevent school violence. Sociology professor Clem Bartollas says kids have become fed up with the violence and are turning in classmates before an incident can take place.He says the school shootings in Littleton, Colorado appear to have pushed the disgust with violence to the saturation point. Students recently turned in a classmate in New York who was planning a Columbine-style attack. He says this is evidence the “code of silence” among teens is breaking down.He says studies on violence and fear in the classroom back up what he’s seeing.Bartollas predicts the number of kids killed in schools will decline dramatically in the next decade.He doesn’t predict there won’t be any more shootings, he says there will be more kids reporting potential problems before a shooting takes place. Bartollas has worked with kids who’ve killed other kids for the last 30 years.