全球化趨勢中，學校學生背景多元，學習差異日益明顯，適性發展教改聲中，學校教師嘗試在課堂中進行差異化教學。任何教學革新不免帶來新擾動，或與既有的教學活動產生矛盾。以往教學研究中，常著眼於教師行為的改變，忽略矛盾所引動的成長趨力。活動理論將系統產生的矛盾視為個體發展的動力，本文藉由個案研究進入一個四年級的數學課堂，探討教師進行差異化教學，面臨的矛盾及實踐轉化特性。研究發現教師出現的主要矛盾包含差異化理論的牽絆、學校課程進度的限制、標籤文化的影響和班級王國的孤立感。然而也因這些困惑，促使老師在既有脈絡中，漸近調整取得認同平衡，進行教學轉化，矛盾成為教師擴展學習的契機。

Due to the trend of globalization, learning differentiation among students with mutli-background has been increasing in schools. School teachers implement differentiated instruction to fit students’ need. Any instructional reform might lead to disturbance or contradictions. This author entered a math differentiated instruction classroom with the perspective of activity theory. It aimed at investigating the nature of contradictions and practical transformation when a school teacher conducted differentiated instruction. It proposed several contradictions in differentiated instruction and suggested that taking contradictions as motive power would be the critical base of practical transformation of teaching reform.