An investigation was made to determine whether teacher expectations influence the way teachers interact with students and, if they do, to assess what effects teacher behavior might have. Also addressed was the question of whether teachers treat males and females differently in ways that may discourage females in math. All teacher/student interactions occurring in a seventh-, an eighth-, and a ninth-grade math class were observed for 10 days each; students and teachers completed questionnaires the year the observations were made and the following year. Student questionnaires measured attitudes, perceptions, values, plans, and conceptions of and about mathematics. Teacher questionnaires elicited teachers' math-related expectations for each student. On the basis of teacher ratings, students were divided into high and low expectancy groups. Results of analyses of variance indicated that high expectancy students received more feedback than did low expectancy students, whereas low expectancy students received more total criticism. Low expectancy females received more teacher attention than did high expectancy females, and males rated high received equal amounts or more attention than did males rated low. Students were found to contribute to classroom interactions by choosing to initiate interactions with teachers and by variously interpreting teacher behavior. Results suggested that teachers could provide more feedback to encourage females in math and to improve males' interaction patterns. (RH)