A study examined English-dominant and Spanish-dominant students' perceptions of opportunities to communicate in science and mathematics classrooms. A survey was administered to 207 Mexican American secondary students who attended a summer enrichment program in mathematics and science at a university on the Texas-Mexico border. The students were typically of high ability and had voluntarily enrolled in the summer program. Primary language was English for 128 students and Spanish for 79 students. Among other areas, the survey examined the frequency of various communication activities in science and mathematics classrooms. These activities included explaining one's thinking, giving oral reports, discussing "current" events, sharing ideas and asking questions, working with others, and writing reports. Two-way analyses of variance were conducted with gender and primary language as independent variables. Results indicate that female students with Spanish as their primary language perceived opportunities to communicate at frequencies nearly equal to those of male and female English-dominant students. Male students with Spanish as their primary language reported the lowest frequencies of participation in classroom discourse in either mathematics or science classes. (Contains 25 references.) (SV)