本研究主要目的在探究小學職前教師數學教學專業發展。研究者以「案例觀察與紀錄」以及「案例分享與討論」作為案例研討路徑，帶領六位職前教師至小學數學課輔現場，以學童的數學學習情況做為「案例」，進行二十二次的案例研討，為期六個月。經由觀察、問卷、與相關文件分析，研究發現：職前教師在案例研討路徑上的數學教學專業發展依序可歸納為焦點模糊、聚焦提問、與嘗試求解三個階段；且其在「關於數學教學的想法與做法」以及「對學習者的理解」兩方面有較為明顯的轉變，至於「數學知識」與「數學課程知識」的進展則較為有限；而此案例研討路徑對職前教師專業成長的牽引主要來自教學現場觀摩、與學童面對面接觸、成員的問題交流、研究團隊的支援與在職教師的經驗分享等面向。

The main purpose of this study was to investigate pre-service teachers' professional development on mathematics instruction. Through a workshop on mathematical teaching, six pre-service teachers participated in observing the mathematical learning of students in an elementary school for six months. "Case-observe-record" and "case-share-discuss" were used as an approach to enhance and investigate the professional development of participants. Through observation, and analysis of questionnaires and related documents, the results revealed that there were three stages of participants' professional development during the period of observation in schools: "without sense," "focus and question," "try to find solutions." Participants' thinking and actions toward mathematical teaching were improved, as well as their understanding of students' mathematical learning. In the context of case-based observation and discussion, the main influential factors in participants' changes were observation in the teaching field, face-to-face contact with students, problem sharing among participants, and support from the researcher and in-service teachers. However, for enhancing the mathematical knowledge and curriculum knowledge of participants, the effect of this teacher preparation approach was limited.