當一個國家提高班級內學生數學表現的同質程度時，是否會增強家庭背景對學生數學表現的影響？?了回答這個問題，本研究使用2003年的TIMSS資料庫，共包含47個國家區域的八年級學生與26個國家區域的四年級學生。筆者首先跨國家與跨年級分析家庭背景對學生數學表現的影響，結果發現家庭背景對台灣學生數學表現的影響，從四年級到八年級遽增，約增加了兩倍。台灣八年級學生的數學表現高度受到家庭背景的影響，影響之大，居47個國家區域的前幾名。最後，筆者以同時有四、八年級學生參與的25個國家?分析樣本，運用雙重差分迴歸模型來控制未觀測到的國家間差異，結果發現班級同質程度的提高，會增強家庭背景對學生數學表現的影響。

Does classroom homogeneity enhance the effects of family background on student performance in math? To address this question, this study uses data from TIMSS 2003, which include 47 countries for students at Grade 8 and 26 countries for students at Grade 4. This study starts with a regression analysis of math performance on student family background for each country at each grade level, and the analysis reveals a sharp increase in the effects of family background on the math performance of Taiwanese students from Grade 4 to Grade 8. The results show that the math performance of Taiwanese eighth graders is very heavily influenced by family background from an international perspective. By employing a difference-in-differences methodology which controls for country-level unobserved heterogeneity, this study finds that an increase in the country-level classroom homogeneity from Grade 4 to Grade 8 enhances the effects of family background on student math performance.