ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 59, Number 1
JKCSEZ 59(1)
February 20, 2015 

The purpose of this study was to examine changes in student writings of claim and evidence after group and class discussions; changes in students' critical thinking; and students' perceptions on an argument-based claim and evidence writing approach. Seventy two grade 11 students from two classes of a high school located in Seoul participated in ten chemistry activities using the argument-based claim and evidence writing approach. Claim scores for 9 topics and evidence scores for 10 topics significantly improved after group discussion. There were also statistically significant differences in claim scores for 7 topics and evidence scores for 10 topics after class discussion. Participant students responded to an open-ended survey that group discussion helped them to figure out the problem context and class discussion guided them to provide with more sufficient evidence. There were also statistically significant increases in sub-scores of the Cornell Critical Thinking Test after the intervention.