本文檢討現行分數啟蒙課程，並探索分數課程改進時的理論基礎。 現況檢討，一方面根據調查資料，凸顯教學問題；一方面根據數學課程理論，檢驗現行課程。 分數概念改進時的理論探索，一方面以實徵資料，開啟現實的數學教育理念，並以小組討論方式辯證此理念所揭示的教育原則與學習理論；一方面整理文獻上被證實較有效的診斷教學法的理論基礎與教學原則。綜合後，形成分數啟蒙診斷教學研究的若干課題。

　　　　　This papers analyses the current beginning fractions curriculum used in Taiwan, and seeks for a ground theory in order to improve children's fractions learning. In section one, some specific problems of teaching and learning beginning fractions are analysed based on certain survey data. In section two, problems of the fractions teaching material are analysed in terms of the unique set of textbooks used in Taiwan. In section three, the general situation of teaching, learning and content of fractions are systematically examined based on the mechanistic approach and the structuralistic approach in mathematics curriculum theory. It was found that the implemented fractions curriculum can be characterized by the mechanistic approach, however the intended fractions curriculum tends towards the structuralistic approach. In section four, some problems of the fractions curriculum based on the structuralistic approach are criticized. In section five, the educational principles and learning theory of the realistic mathematics education are introduced via a study in which the process and strategies used by three children in solving the problem of shairing loaves of breads are observed and analysed. In section six, the ideas of realistic mathematics education are dialected via a panel involving ten mathematics educators. In section seven, the principles of mathematics diagnostic teaching are synthesized. In section eight, a ground theory for developing beginning fractions curricrlrm is recommended by integrating the principles of the realistic mathematics education and the diagnostic teaching. Some research problems are then formulated in terms of this theory.