The National Council of Teachers of Mathematics (NCTM), through its Connections Standard, highlights the importance of "the opportunity for students to experience mathematics in a context." Seeing how mathematics can be used to describe real-world phenomena can motivate students to learn more mathematics. Connecting mathematics to the real world is complicated, however, by the diversity of students' cultural and linguistic backgrounds, experiences, and interests. One student's real world likely differs from another's, and the students' real and lived worlds likely differ from those of the teacher's. Mathematics teacher education and professional development programs must, therefore, guide teachers toward learning about their students. Knowledge about students helps teachers incorporate students' out-of-school knowledge, experiences, and interests into mathematics teaching and learning. In the professional development unit presented in this article, teachers explore maps at four levels of scale--global, national, regional, and local--and these explorations make explicit a variety of ways that maps can be used as a context for mathematical investigations. More significantly, however, the unit provides teachers with opportunities and strategies for learning about their students, students' families, and school communities. (Contains 7 figures.)