1 Introduction

This section introduces the challenges of improving school after-class services under the "Double Reduction" policy, highlighting issues such as uneven distribution of curriculum resources and teacher competency. It emphasizes the importance of establishing a collaborative development framework involving "universities—local governments—primary and secondary schools" to address the supply-demand imbalance in after-class services. This study focuses on a case of English teacher candidates participating in after-class services, aiming to explore their personal experiences and professional development as they translate theory into practice.

2 Literature Review

This section discusses the concept and practice of collaborative teaching, underscoring its significance in teacher professional development. Collaborative teaching involves two or more teachers jointly planning lessons, delivering instruction, and evaluating outcomes. For pre-service teachers, it serves as a pathway to gain emotional and professional support while enhancing teaching skills. The study integrates collaborative teaching with a mentorship model, where teams of English teacher candidates take turns teaching under the guidance of professional mentors, both online and offline. Additionally, the chapter explores the definition and dimensions of teacher professional development, citing Evans' three-dimensional structural model to analyze the behavioral, attitudinal, and cognitive aspects of in-service teachers' professional growth. The study proposes applying this model to examine the professional development of English teacher candidates in after-class services, testing its applicability to pre-service teacher research.

3 Research Design

This section outlines the qualitative case study methodology, aiming to investigate the feasibility and effectiveness of team-based teaching in after-class services under the guidance of professional mentors. The research questions focus on teacher candidates' experiences with mentor-led team teaching and how collaborative after-class services contribute to their professional development. The study context involves two after-class service courses offered by a normal university at a secondary school in September 2022, taught by 64 English teacher candidates. The participants include 12 junior and senior students selected through stratified and convenience sampling. Research tools encompass interviews, reflective journals, lesson plans, and teaching videos for triangulation. Data analysis combines inductive and deductive approaches, involving content extraction, identification of local concepts, coding, thematic integration, and validation. To ensure credibility, the researcher shared case descriptions with participants for confirmation and engaged an assistant for independent coding and comparison.

4 Findings

The case study reveals the experiences and professional development of English teacher candidates participating in after-class services under the "Double Reduction" policy. Findings show that teacher candidates underwent complex emotional experiences, ranging from initial excitement and pride to stress and anxiety, and ultimately to a sense of accomplishment and fulfillment. In terms of collaborative experiences, teacher candidates benefited from positive teamwork under mentor guidance, with notable collaboration between junior and senior students. Mentors provided critical support in lesson design, classroom management, and post-teaching reflection.

Regarding professional development, teacher candidates demonstrated growth in cognition, attitude, and behavior. Cognitive development was evident in their enhanced ability to analyze teaching and deepen their understanding of pedagogy, as they learned to design lessons from students' perspectives and grasp the relationship between teaching and learning. Attitudinal development involved strengthened self-awareness, increased career motivation, and a deeper perception of the teaching profession. Behaviorally, teacher candidates improved their language proficiency, classroom management skills, and acquired practical teaching strategies.

Specifically, during lesson refinement, teacher candidates advanced their analytical skills, shifting focus from "what to teach" and "how to teach" to "how to facilitate learning." Their pedagogical understanding evolved as they began reflecting on teaching from theoretical perspectives and interpreting theory through practical teaching. In self-perception, they developed objective self-evaluations and identified areas for improvement. Career-wise, they found love and fulfillment in after-class services, reinforcing their commitment to teaching. Professionally, they recognized teachers not only as knowledge transmitters but also as mentors and friends, bearing the responsibility of nurturing students. Behaviorally, they honed language and classroom management skills while accumulating practical strategies such as engaging student interest, assessing learning outcomes, and managing instructional time.

5 Discussion

This chapter discusses the professional development of teacher candidates in after-class services under the "Double Reduction" policy. Findings indicate that team-based teaching enhances their emotional experiences, collaboration skills, teaching analysis abilities, professional perception, motivation, language proficiency, and classroom management. These align with Evans' three-dimensional model, emphasizing cognition, attitude, and behavior as core elements of pre-service teacher education. Teacher candidates' professional development relies on the "affordances" of collaborative teaching, individual agency, and mentor support. Effective collaborative teaching requires consideration of peer compatibility, accountability, and rational task allocation, while teacher candidates' agency manifests in resource selection, judgment, and decision-making. Professional mentors play multifaceted roles in collaborative teaching, critically shaping teacher candidates' growth.

6 Conclusion

This chapter highlights how the study provides empirical support for normal universities' involvement in school after-class services and underscores the importance of innovative pathways for teacher candidate education. It proposes measures such as improving selection and collaboration mechanisms, fostering teacher candidates' agency, and ensuring professional mentorship to facilitate after-class services. The study also acknowledges limitations and suggests future research expand to examine the experiences and gains of mentors and secondary students.