Stoichiometry, which deals with the quantitative aspects of Chemistry, is a topic students find challenging and which teachers struggle to teach. South African students’ performance in stoichiometry in the final matriculation examinations has led to calls for the topic to be taught better and highlighted the need for teacher professional development. This served as the rationale for this study to design an instrument to measure the quality of experienced Physical Science teachers’ topic-specific pedagogical content knowledge (TSPCK) using a mixed-methods approach. Responses by five teachers to open questions on each of five components of TSPCK were used to generate scenario-based items for the instrument. The validity of the instrument was determined through Rasch analysis of responses of a sample of 31 teachers. Both the validity and reliability of the instrument to measure the quality of TSPCK in stoichiometry were found to be acceptable based on the fit statistics and reliability measures generated from the Rasch analysis.

中文翻译：

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化学计量学中测量体育教师主题特定的教学内容知识的工具的有效性和可靠性

化学计量学涉及化学的定量方面，是学生发现的挑战和教师难以教授的话题。南非学生在最后的入学考试中的化学计量学表现促使人们呼吁更好地教授该主题，并强调了教师专业发展的需要。这是本研究的理由，旨在设计一种使用混合方法来测量经验丰富的物理科学教师的主题特定的教学内容知识（TSPCK）的质量的工具。由五名教师对TSPCK的五个组成部分的每一个提出的问题的回答被用来生成基于情境的工具。该仪器的有效性是通过对31位教师的样本进行的Rasch分析确定的。