Quantifying the effect of peer interaction on second language students' written argument texts

This paper reports on a quasi-experimental study investigating the effects of interaction on the writing of argument texts by second language (or NESB ) students in a high school. Results are compared on variables related to t he conventional text quality measures: communicative quality; ideas and org anisation; and grammatical accuracy and complexity. The results indicate be nefits for working in a solitary way. When students worked alone, their tex ts resulted in significantly better mean scores for grammatical accuracy an d complexity. This paper seeks to explain this finding by analysing the pos sible sources of constraints on performance experienced by students with la nguage backgrounds other than English.