Introduction

Recent changes in education policy emphasize promoting school-to-school support and school-led improvement to enhance resource sharing and build a professional learning network for high-quality and balanced education (Ainscow et al., 2006; Muijs, 2015; Muijs et al., 2010; Liu, 2018). In China, the government encourages prestigious public schools to support weaker public schools, with supporting teachers sent from prestigious schools to implement improvement missions. Existing studies have focused on the willingness of supporting teachers to rotate to weaker schools and its influencing factors (e.g., Du et al., 2018; Zhang et al., 2023), with limited research on how these teachers undertake the support work (e.g., Zhong et al., 2018; Zhang & Ye, 2023; Qian et al., 2023). The assessment culture differences between supporting and weaker schools greatly influence the process and assessment of school improvement. The supporting schools and teachers often represent a student-centered educational philosophy, in line with the Chinese new curriculum reform, while weaker areas often focus on test and score-oriented education. However, little research exists on how supporting teachers actively engage in assessment reform to promote teaching and learning reform in supported schools. Therefore, this paper aims to explore how supporting teachers employ their assessment literacies to foster teaching and learning reforms in the schools they support and the strategies they use to span across boundaries.

Boundary spanning practice and boundary object

The concept of 'boundary spanning' arises when individuals venture into unfamiliar territory and must navigate and merge elements from different contexts to create hybrid situations (Engeström et al., 1995). Those who engage in this practice are known as boundary spanners, connecting various communities of practice and facilitating relationships between them (Wenger, 1998). Their activities involve establishing routines that uphold connections between different communities of practice or stakeholders and providing a platform for ongoing engagement in professional activities. To achieve this, leaders may utilize boundary objects (Star and Griesemer, 1989) , which are tangible items or artifacts that exist within multiple communities of practice, serving as a means of translation within multi-site work relations and requirements. The role of individuals as boundary spanners requires the ability to manage and integrate diverse discourses and practices across social boundaries. Additionally, educational infrastructure is essential to foster interactions and networks across schools or communities of practice, support boundary practices, and sustain improvement (Spillane et al., 2016).

Teacher assessment literacies framework 

Assessment is a vital element in education, impacting teaching and learning. Teachers' assessment literacy involves understanding the assessment process, the interaction between assessment and teaching, and the ability to conduct assessments effectively (Stiggins, 1991). The focus has shifted towards "assessment for learning," emphasizing teachers' ability to review students' learning and performance data and develop programs that support student learning. Teacher assessment literacy is a dynamic and context-dependent social practice, involving the articulation and negotiation of classroom and cultural knowledge to achieve student learning goals through assessment (Adie et al., 2020; Ataie-Tabar et al., 2019; Baker & Riches, 2018; Schneider, Deluca, Pozas & Coombs, 2020; Willis et al. 2013). Scholars have redefined the framework of teacher assessment literacy, emphasizing aspects such as selecting appropriate assessment methods, interpreting results, providing student guidance, and using assessments for instructional design and school improvement (Brookhart, 2011). There is also a growing emphasis on the ethical dimensions of teacher assessment, including managing ethical conflicts, upholding fair assessment ethics, and addressing student cheating (Pope et al., 2009; Pastore et al., 2019).

Method This paper seeks to understand the supporting teachers' assessment initiatives in recipient schools, employing a qualitative research approach. The Research site The study will based on the educational support of School Z to School X. School Z, located in a the capital city in China, is at the forefront of national and global education reform, with a focus on using assessment to enhance learning and promote core competencies. In contrast, recipient School X, situated in a province that lags behind in national curriculum reform, emphasizes score-oriented teaching and lacks integration of teaching and assessment. The school also faces challenges such as large class sizes, shortage of professional teachers, and limited assessment feedback to guide and motivate learning. The contrasting assessment cultures at School Z and School X represent the two poles of the integration of teaching and assessment in Chinese schools. Studying how supporting teachers from School Z conducts assessment reforms at School X can provide valuable insights into inspiring improvement. Data collection Z School's support for X School began in March 2018, with 12 supporting teachers dispatched in September of the same year. The first author established a partnership with the team from the start and actively participated in and witnessed most of the support work, collecting data through participatory observation, interviews, and material collection. Participatory Observation: The author visited X School on three occasions, observing classroom lessons, participating in teaching research, and taking part in the selection of teaching innovation awards and X School's guidance on promoting teachers' development through subject research. Interviews: Formal and informal interviews were conducted with the support team, the director of local education bureau, the leadership of X School, and teachers at X School who actively responded to the reforms. Materials Collection: Textual materials were collected, including systems and measurement standards developed by the assistance team, updates on the school's WeChat platform, application materials for the school-based Teaching Innovation Award, and project proposal documents. This also includes reports from the assistance team and assisted school teachers on various occasions. Data analysis This study is rich in data. Researchers focused on data closely aligned with the research question, conducting preliminary data selection based on relevant data. Further data selection was carried out around major themes, and the extracted data was then summarized to ensure unique insights into teacher assessment reform in the context of China's assistance.

Conclusions The study found that supporting teachers at X School conducted the following work to build an assessment for learning culture: Established clear curriculum development objectives to guide students' learning. Expanded teachers' understanding of assessment, diversified assessment methods, and enhanced formative assessment. Fully utilized the educational function of homework. Actively developed students' self-assessment ability. Actively implemented "focus on every student's learning, treat every student fairly and justly" assessment ethics. Led stakeholders to establish a unified assessment philosophy. Built the infrastructure support required for assessment reform. The findings are consistent with international discussions on the teacher assessment framework, emphasizing assessment to enhance learning, the integration of teaching and assessment, core quality and competency-based learning assessment, students' self-assessment, and respect for students. The support team also identified a dimension that has not been mentioned in the international literature. This dimension involves developing the mindset of parents and other education stakeholders towards assessment for learning, with the aim of reforming the local assessment culture. To promote a change in mindset, supportive teachers utilized various boundary objects, such as reallocating and decorating school spaces, developing guidelines for teaching and assessment, and reporting school activities from a student-centered perspective. The study also found that different supporting teachers did not adopt the same strategies for assessment practice. They engaged in collaborative discussions and combined individual exploration with their understanding of their teaching subject, teaching characteristics, and prior educational experiences. This personalized exploration fostered professional learning and development. The study suggests that teacher education should prioritize the development of teachers' skills in promoting learning through assessment. The current implementation of "Assessment to Promote Learning" still requires strong top-down support in the context of the new era.

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