1　Introduction

This section introduces the practical dilemmas faced by primary and secondary schools in after-school services under the "Double Reduction" policy in 2021, including shortages of curriculum resources and teaching staff. It points out that establishing a "university-local government-school" community is an effective path to alleviate the supply-demand contradiction, and notes that current research on after-school services remains largely theoretical with insufficient empirical exploration. The study thus clarifies its focus on a case study of a normal university, examining English normal students' personal experiences and professional development processes through their participation in after-school services via cooperative teaching.

2　Literature Review

This section reviews two core concepts: cooperative teaching and teacher professional development. Cooperative teaching refers to multiple teachers collaborating in the same classroom, covering lesson preparation, instruction, and assessment. It can promote in-service teachers' growth and is also a common practice model for pre-service teachers abroad. This study introduces it into English normal students' educational practice for the first time, adopting a combination of team teaching and mentoring models, where normal students form teams to take turns teaching while professional teachers provide online and offline guidance on curriculum development, instructional design, implementation, and reflection. Teacher professional development refers to systematic efforts to change teaching practices, beliefs, and student learning outcomes, involving changes at personal, professional, and social levels. Evans' (2011) three-dimensional structural model based on sociocultural theory deconstructs it into behavioral, attitudinal, and cognitive dimensions. This model is mostly used to evaluate the effectiveness of professional development activities, but existing research focuses primarily on in-service teachers. This study uses this model as a framework to analyze normal students' professional development in cooperatively conducting after-school services and to verify its appropriateness in pre-service teacher research.

3　Research Design

This section introduces the design framework of a qualitative case study to explore the feasibility and effectiveness of conducting after-school services under a mentor-led team teaching model. The research context involves two after-school courses offered by a normal university at a middle school in September 2022. Sixty-four English normal students applied voluntarily and were selected to form groups of 4–6 members to undertake teaching tasks. The study employed stratified and convenience sampling to select 12 junior and senior students as participants, using interviews, reflective journals, lesson plans, and teaching videos for triangulation, accumulating 636,000 words of data. Data analysis combined inductive and deductive methods, extracting four themes—"after-school service experience," "teacher cognition," "teacher attitude," and "teacher behavior"—through five-level coding, and ensuring research credibility through member checking and independent coding comparison.

4　Research Findings

This section presents English normal students' experiences and professional development in after-school services. In terms of emotional experience, normal students underwent a dynamic process from initial "happiness" and "pride" to subsequent "pressure" and "anxiety," then to "frustration" and "pain" during lesson polishing, and finally to "excitement" and "happiness" after completing instruction. In terms of cooperative experience, the mentor-led team teaching model provided positive experiences for normal students. Mixed-grade groups of juniors and seniors formed complementary advantages, mentors provided "scaffolding" guidance before, during, and after class, and assumed the role of "cooperation mediator" to resolve team conflicts.

Normal students' professional development was manifested in three dimensions: In cognitive development, repeated lesson polishing enhanced instructional analysis abilities, shifting focus from "what to teach" to "how to facilitate learning," deepening instructional understanding, forming correct perceptions of individual student differences and the relationship between "teaching" and "learning," and beginning to use theoretical terminology to reflect on practice. In attitudinal development, normal students formed objective self-evaluations, recognizing their strengths in information processing and lesson plan writing as well as weaknesses in classroom interaction and time management. Their career motivation significantly increased, strengthening their determination to teach. They developed profound understanding of teacher identity, qualities of excellent teachers, and the connotation of teacher professional development, transforming external requirements into internal development motivation. In behavioral development, classroom language became more concise and standardized, classroom management abilities improved through micro-skill application and instructional design refinement, and practical strategies were accumulated for stimulating interest, assessing learning effects, and controlling instructional time.

5　Discussion

This section examines the professional development mechanism of normal students participating in after-school services through the team teaching model, finding growth in all three dimensions—cognition, attitude, and behavior—and verifying the appropriateness of Evans' three-dimensional structural model for pre-service teacher research. Normal students' professional development depends on three conditions: the cooperative teaching format optimizes "affordances" in the learning environment, creating opportunities for development; normal students exercise agency to transform affordances, undergoing a process from perceiving resources to taking action; and professional mentors provide scaffolding support. Because after-school services lack grade assessment, mentors' evaluator role is weakened while their support function is strengthened. Mixed-grade groups gain better cooperative experiences through reasonable division of labor, and conflicts also become learning opportunities.

6　Conclusion

This study provides empirical support for normal universities' participation in primary and secondary schools' after-school services and for innovating normal students' educational practice paths. It proposes improving selection and cooperation mechanisms to mobilize normal students' agency and promoting their cooperation and teaching abilities through professional mentor guidance. It also notes that future research could expand to mentors' and middle school students' experiences and gains.