This mixed method study analyzes rural migrant children's academic experiences in two Shanghai public schools when 2012 PISA scores were administered. It contributes empirical evidence on how hukou status shapes educational inequality in contemporary China. Since rural migrants are ineligible for the high-stakes test for Shanghai's senior secondary admission, teachers diverted resources towards urban children at the expense of rural migrants, regardless of academic potential. Such "successful" teaching practices to maximize ranking motivated excessive resource provision to the detriment of urban youth's development. This article argues that it is only possible to understand these patterns through an inequality theory that explicitly considers the diminished integrity of teaching in high-stakes testing contexts. The framework explains educational injustices when the moral assumption of "good" teaching to benefit a child is no longer valid, with implications on the growing global emphasis on high-stakes testing.