摘要：The present study adopts a quantitative design to explore the effects of pre-designed teachers' questions as the mediation tool to scaffold the development of students' critical thinking and their discourse level writing skills in English from a sociocultural perspective. The participants were 39 sophomores from two classes. The results showed that:(1) teachers' questions targeting specific critical thinking skill in the classroom and in after-class conferences, as well as in written homework feedback were effective;(2) students backslid a little while internalizing teachers' questions concerning critical thinking;(3) students improved reliably in terms of local and global coherence in their written production with the help of teachers' questions. The findings indicate that teachers' questions facilitate students' development of critical thinking and enhance their discourse level writing skill.