This article describes a cleaned and structured dataset derived from a systematic large-scale survey conducted through official administrative channels of approximately 3400 primary school teachers and educational administrators in Vietnam, which was refined to 2772 valid responses after data cleaning and quality control procedures. The dataset focuses on instructional practices and the use of assessment data in Grade 5, within the context of the implementation of the 2018 General Education Curriculum. Key variables include teaching experience, instructional adaptation, use of assessment data, and classroom support practices. The dataset underwent systematic cleaning, scale harmonization, and validation procedures, including reliability analysis and exploratory factor analysis. These procedures document the internal consistency and empirical structure of the constructed variables and provide supporting information for researchers interested in reusing the dataset for secondary analyses. The dataset provides a large-scale empirical resource for investigating teacher practices during a major curriculum reform and offers opportunities for secondary and comparative research in primary education.
