It is the premise of this study that the performance of black students in math and science is crippled by the interference of their language patterns. It is argued that schoolwork of these students demonstrates how nonstandard English can lead to misunderstanding. The connection between students' misunderstandings of certain quantitative relations and their nonstandard use of particular prepositions is explored, as is the way in which the combining of standard English "as" and "than" leads to a lack of distinction between addition and multiplication between subtraction and division and thus to a confusion between "twice" and "half." How students' nonstandard ways of expressing partitive comparisons are related to their nonstandard perceptions of division is also examined. By placing these errors and misunderstandings in the context of linguistic interference, this book challenges teachers and administrators to rethink their methods for improving the educational performance of minority students. An Afterword presents ways of thinking about the linguistic differences of minority students based on observations of the daily work of the socially and ethnically mixed student population of the Hawthorne School in Washington, DC. (VM)