Title: Learning how to use evidence in argumentation
Description: How does argumentive writing develop as young adolescents examine evidence and engage in rich peer discourse on a succession of four topics (13 class sessions each) over an academic year? Three classes participated, one randomly assigned to a control group and two to experimental groups. In a supporting-evidence experimental group, students only examined evidence that supported their own favored position on a topic. In a mixed-evidence experimental group, students examined multiple types of evidence that supported their position, weakened their position, supported the opposing position, or weakened the opposing position. A control group was not provided any evidence. In individual final essays on each of the topics, both experimental groups included more evidence-based statements and were more successful in using evidence functionally to address a claim, compared to the control group. The experimental groups did not differ from one another in the employment of evidence-based arguments that supported their own position and both groups surpassed the control group in this regard.

The mixed-evidence group exceeded the supporting-evidence and control groups in the successful use of evidence that weakened the opposing position; the supporting-evidence group also surpassed the control group in this regard. In use of evidence that supported the opposing position there was an effect of time, with performance improving over time, and an interaction between time and condition with the mixed-evidence group surpassing the control group by topic four. (There was low incidence of, and no significant effects for, use of evidence that weakened own position.) In a final year-end transfer assessment, all students wrote on a novel topic and had access to the same set of mixed evidence. Evidence use on this essay showed a condition effect, with the mixed-evidence intervention group using more evidence than either of the other two groups (who did not differ from one another). However, in contrast to their essay writing on the topics with which they had deep engagement during the intervention itself, these essays by the mixed-evidence group on a novel topic included with little exception only evidence to support their own position.

Even though they were able to show their skill in using the range of types of evidence when they had gained familiarity with the topic, the lack of experience with the transfer topic limited their ability to fully implement their skills in using evidence in argument. These findings suggest that students’ argumentive writing, specifically with respect to the use of evidence, benefits from experience with a variety of forms of evidence, including evidence that weakens as well as supports claims. More broadly, these findings support dialogic argumentation as a productive technique in the development of student’s individual argumentive writing.