Abstract
This study examined the mediating role of mathematics performance and the moderating role of teacher-student relationships on the effects of problematic smartphone use on students' subjective well-being. Through probability proportionate to size sampling (PPS), a total of 20,321 fourth graders from a city in central China were invited to complete a paper-based mathematics achievement test and an online questionnaire survey, including demographic information, problematic smartphone use, subjective well-being, and teacher-student relationship scales. The results showed that: after controlling for SES and gender, (1) problematic smartphone use had a direct and negative effect on students' subjective well-being; (2) mathematics performance partially mediated the effects of problematic smartphone use on students' subjective well-being; (3) teacher-student relationships moderated the effects of problematic smartphone use on mathematics performance/students' subjective well-being; (4) with the increase in problematic smartphone use, high teacher-student relationships produced a lower rate of the positive moderating effect than low teacher-student relationships. The implications of this study and suggestions for future research are discussed.