How teacher support and practical environment relate to engagement in project-based learning: the mediating roles of self-efficacy and autonomous motivation

Abstract

Background Project-based learning (PBL) has been widely adopted in higher education, including Chinese universities, to promote active, interdisciplinary, and applied learning. Yet sustaining deep student engagement in demanding project environments remains a challenge, and existing research has largely examined instructional, environmental, and individual factors in isolation rather than within an integrated framework. Drawing on self-determination theory and social cognitive theory, this study distinguished two forms of contextual support, namely teacher behavior and support (TBS) and practical environment and support (PES), and examined how they relate to student engagement through self-efficacy (SE) and autonomous motivation (AM). Methods A cross-sectional survey of 511 undergraduates enrolled in interdisciplinary PBL courses at a university in eastern China was analyzed using partial least squares structural equation modeling (SmartPLS 4), following a two-step procedure with 5,000 bootstrap resamples and blindfolding for predictive relevance. Common method bias was assessed through Harman's single-factor test, a full collinearity assessment, and a marker-variable adjustment. Results The measurement model demonstrated satisfactory reliability, convergent validity, and discriminant validity. The structural model explained 56.8% of the variance in student engagement and showed adequate predictive relevance (Q2 > 0.28 for all endogenous constructs). TBS and PES had significant direct effects on engagement and significantly predicted SE and AM. Both SE and AM, in turn, significantly predicted engagement. Bootstrapped mediation tests confirmed four significant indirect pathways, indicating partial mediation. Notably, PES had large effects on SE (f2 = 0.476) and AM (f2 = 0.424), while SE showed a numerically larger coefficient than AM in predicting engagement (β = 0.307 vs. 0.175), although the difference did not reach statistical significance. Conclusion These findings suggest that PBL engagement is associated with dual pathways: contextual support relates to students' confidence and their autonomous motivation, which together relate to sustained engagement in project work. By integrating the two theoretical frameworks and distinguishing interpersonal from structural support, the study highlights self-efficacy as a psychological resource that appears comparatively central in complex project environments, informing the design of more effective PBL environments.