According to the Times of India, a study examined students' performance and attitudes in mathematics and science; verbal skills; and attitudes toward school, gender stereotypes, aggression, victimization, and body image. The total sample included 1,663,662 participants in 21 different countries. They did not find enough evidence showing any difference in these attitudes between boys and girls in single-sex classes. The research, which analyzed 55 years of data, disproves theories that girls thrive when separated from boys, and that boys perform better when they have a program specifically tailored to them. needs. Although single-sex schools achieve exceptional exam results, there is no strong evidence that this is due to the separation of boys and girls. Since many single-sex schools are selective, their good exam results could be due to having academically advanced students and more demanding teaching programs. Single-sex classes face failure due to lack of proper training and infrastructure. Global research by the University of Nebraska showed that 71% of teachers felt they were not adequately trained for the move to single-sex classrooms. According to a report published in the journal Science, the researchers wrote: "Sex-segregated education is deeply flawed and often justified by weak, cherry-picked, or misinterpreted principles.".