Abstract
This research examined changes in the paragraph-writing performance of 32 first-year English-majored students during a blended course at a public university in Hanoi. A single-class pre-test/post-test design was used. Following baseline assessment and orientation in Weeks 1–2, students completed blended activities from Weeks 3-10, combining asynchronous preparation on Google Classroom with face-to-face instruction, guided practice, peer interaction, drafting, and feedback. The post-test was administered in Week 11, followed by an 11-item questionnaire and semi-structured interviews with three purposively selected students in Week 12. Paired-samples t-tests indicated a significant increase in overall writing scores, with significant changes in content, organization, and grammar but not vocabulary. The questionnaire scales showed high internal consistency, and students reported favourable perceptions of engagement, motivation, confidence, and autonomy. Interview accounts illustrated perceived improvements in organization while also identifying distraction, unclear instructions, comprehension difficulties, and access constraints. Overall, higher post-test scores were observed after eight weeks of substantive blended instruction. However, the single-group design cannot isolate the contribution of blended learning from regular instruction, practice, feedback, task familiarity, or maturation.