Inquiry-based science teaching (IBST) is a key goal of science education reforms worldwide. Recent research highlights the importance of infusing inquiry teaching with knowledge about the nature of scientific inquiry, and not just focusing on procedural skills to do inquiry. However, such an endeavour requires teachers to have high levels of self-efficacy. Given the lack of valid and reliable measurement instruments for Spanish-speaking teachers, the present study adapted and validated Aydeniz et al. Science and Education, 30(1), 103–120, (2021) Inquiry-Based Science Teaching Efficacy Scale (IBSTES, Science & Education, 30:103–120). Confirmatory factor analysis on data from 428 pre-service teachers in kindergarten and elementary school revealed a two-factor structure, which is consistent with the conceptual framework of IBST. The two factors measured self-efficacy beliefs regarding (1) helping students improve their understanding of the nature of scientific inquiry and (2) helping students develop procedural skills for conducting scientific inquiry. Both factors demonstrated very high reliability (> 0.90), as assessed by Cronbach's alpha and McDonald's omega. This latent structure was invariant across genders, suggesting that the instrument can be used with both male and female prospective teachers, allowing for gender comparisons. This study is the first of its kind to validate in Spanish a self-efficacy scale for IBST that specifically tackles the epistemological understanding of the nature of scientific inquiry. The Spanish IBSTES provides a valuable tool for researchers and practitioners to assess and support teacher self-efficacy, which is essential for the success of educational reforms.
