This study aimed to verify the validity of a measurement tool for Vietnamese high school students’ systems thinking abilities. Two quantitative assessment tools, the Systems Thinking Measuring Instrument (Lee et al., 2013) and the Systems Thinking Scale (Dolansky et al., 2020), were used to measure students’ systems thinking after translation into Vietnamese. As a result, it was revealed that Cronbach-α for each tool (i.e., STMI and STS) was .917 and .950, respectively, indicating high reliability for both. To validate the construct validity of the translated questionnaire, exploratory factor analysis was performed using SPSS 26.0, and confirmatory factor analysis was performed using AMOS 21.0. For concurrent validity, correlation analysis using structural equation modeling was performed to validate the translated questionnaire. Exploratory factor analysis revealed that 10 items from the STMI and 12 items from the STS loaded on the intended factors and appropriate factor loading values were obtained. For confirmatory factor analysis, a structural equation model organized with 10 items from the STMI and 12 items from the STS was used. The result of this showed that the convergent validity values of the model were all appropriate, and the model fit indices were analyzed to be χ 2 /df of 1.892, CFI of .928, TLI of .919, SRMR of .047, and RMSEA of .063, indicating that the model consisting of the 22 items of the two questionnaires was appropriate. Analysis of the concurrent validity of the two tools indicated a high correlation coefficient (.903) and high correlation (.571-.846) among the subfactors. In conclusion, both the STMI and STS are valid quantitative measures of systems thinking, and it can be inferred that the systems thinking of Vietnamese high-school students can be quantitatively measured using the 22 items identified in our analysis. Using the tool validated in this study with other tools (e.g., qualitative assessment) can help accurately measure Vietnamese high school students’ systems thinking abilities. Furthermore, these tools can be used to collect evidence and support effective education in ODA projects and volunteer programs.

I. Introduction
II. Method
    1. Context of the Study
    2. Participants and Data Collection
    3. Measuring Tools
    4. Data Analysis
III. Results
    Result 1. Exploratory Factor Analysis
    Result 2. Confirmatory Factor Analysis
    Result 3. Analysis of Concurrent Validity
IV. Discussion and Conclusion
V. Limitations

• Hyonyong Lee(Department of Earth Science Education, Kyungpook National University, Daegu 41566, Korea)
• Nguyen Thi Thuy(Thuan Hoa High School, Hue 54000, Vietnam)
• Hyundong Lee(Department of Science Education, Daegu National University of Education, Daegu 42411, Korea)
• Jaedon Jeon(Science Education Research Institute, Kyungpook National University, Daegu 41566, Korea)
• Byung-Yeol Park(Department of Curriculum and Instruction, Neag School of Education, University of Connecticut, CT 06269, USA) Corresponding author