This study explores the correlation between teachers' remarks regarding language correctness and style and upper secondary school students' grades. The material consists of assignments from three different classes, with two different teachers. The purpose is to investigate a possible connection between the teachers' remarks regarding the use of improper language and the students grades. The result of this study clearly demonstrates that the more remarks a student receives regarding improper language, the more he or she is likely to get a lower grade. The two teachers tend, however, to assess language use somewhat differently: the first teacher tends to value formal writing higher than the other one, who rather tends to appraise semantic strincency.