This study of gender differences in mathematics learning examined two 4-year-olds who attended a Melbourne, Australia preschool. The study traces the experiences of the students, one female and one male, during their first formal exposure to mathematics in kindergarten. Of particular concern was how the preschoolers interacted with their teacher, the ways in which the students processed the explanations of important mathematical concepts given by the teacher, and the ways in which they approached and handled unfamiliar mathematical problems. Research has indicated that teachers often interact differently with their male and female students, with males attracting more interactions. Findings showed substantial differences in the students' involvement during relatively formal, teacher-led sessions concerned with exploring and developing mathematical concepts. The students differed in their response to teacher questions and their patterns of offering unsolicited comments or initiating interactions with the teacher. As a result, the male student's visibility was higher than the female's. The teacher's mode of instruction contributed to higher male visibility and to the provision of opportunities to confirm or challenge students' emerging understandings. (SH)