Background Teachers in high-stress roles face increasing psychological distress such as anxiety and depression, underscoring the need for validated assessment instruments. Given the current absence of a comprehensive, designated, and time-efficient scale capable of evaluating depression, anxiety, and stress among the teacher population, the Depression, Anxiety, and Stress Scale-21 (DASS-21) presents itself as a promising alternative. Despite the widespread application of the DASS-21 for assessing psychological distress across various populations, its validity among teachers, along with questions about its factor structure and its potential property of time equivalence, remain unverified. This study endeavors to address these considerations by investigating the psychometric properties of the DASS-21 specifically within the population of Chinese primary and middle school teachers. Methods Cross-sectional (n = 9,030) and longitudinal surveys (n = 1,642) were conducted using a non-probability sampling method. In addition to the DASS-21, the Chinese version of Chinese Teachers’ Job Burnout Questionnaire (CTJBO) was utilized to evaluate the criterion validity of this scale. Three different approaches, namely confirmatory factor analysis, Rasch analysis, and network analysis, were employed to evaluate internal reliability, construct validity, as well as time invariance of the DASS-21. Results The DASS-21 demonstrated a high degree of internal consistency (Cronbach’s α > 0.85) as well as excellent convergent validity, despite poor discriminant validity as determined by average variance extracted. Confirmatory factor analysis and network analysis further supported convergent validity. The three-factor structure outperformed one- and two-factor alternatives, establishing time invariance. Rasch analysis at the item level identified six inappropriate items within the anxiety and stress subscales, which were subsequently removed. Network analysis presented a better revised network. Regression analysis with emotional exhaustion as the criterion provided logical and accurate results. Conclusion The DASS-21 was found to be a reliable and valid tool for measuring the mental health of teachers over time. To assess the instrument’s psychometric properties, a combination of confirmatory factor analysis, Rasch analysis, and network analysis was utilized, which proved effective and is recommended for evaluating contentious instruments. Based on the results of the study, researchers and healthcare professionals are recommended to use the DASS-21 for assessing teachers’ psychological distress. However, certain items identified in the study may need to be removed to enhance the instrument’s appropriateness for this specific population.

Collaboration proves to be an effective way to facilitate students’ engagement and solve the mostly-mentioned problems of blended learning (BL). For collaborative BL, self-regulated learning (SRL), self-efficacy and engagement are frequently referred to in BL studies and represent key elements of effective BL. Furthermore, the interaction of these elements correlates closely with the performance of students. There have been few research attempts to draw synergies and explore the relationship among these key elements. To address this gap, data were collected through a questionnaire and records on LMS from 125 students in a Chinese university. Descriptive analytics show that students fully recognize the positive effects of collaborative BL. Correlation analysis and regression analysis find that self-regulated learning (SRL) is significantly correlated with all factors except workload. It is also a significant predictor of behavioral engagement. Therefore, SRL proves to be central among the essential BL elements. Emotional engagement is significantly correlated to and interact with multiple key BL factors. Specifically, emotional engagement is a significant predictor of behavioral engagement. The findings offer insight into the interactions of key elements of BL and provide practical implications for improving BL learning design.

During transitional periods, college freshmen may experience mental health issues. The Depression, Anxiety, and Stress Scale—21-item version (DASS-21) is commonly used for mental health assessment in China. However, evidence is lacking regarding its applicability with freshmen as a demographic. Debates also exist regarding its factor structure. This study aimed to evaluate the DASS-21′s psychometric properties with Chinese college freshmen and investigate its association with three kinds of problematic Internet use. A convenience sampling method was used to recruit two samples of freshmen—one of 364 (female 248; mean age 18.17 years) and the other of 956 (female 499; mean age 18.38 years) participants. McDonald’s ω and confirmatory factor analysis were conducted to evaluate both the scale’s internal reliability and construct validity. The results indicated acceptable reliability, with a one-factor structure inferior to a three-factor structure in terms of model fit. Furthermore, it was demonstrated that problematic Internet use was significantly and positively associated with depression, anxiety, and stress among Chinese college freshmen. Based on the prerequisite of measurement equivalence across two samples, the study also found that freshmen’s problematic Internet use and psychological distress were likely to be affected by the strict measures put in place during the COVID-19 pandemic.