ON AN unseasonably warm fall afternoon, I stood in the back of a chemistry classroom in one of the most economically disadvantaged urban areas in the U.S. and watched a sea of sleepy black and brown faces painted with confusion, frustration, and indifference as their teacher taught them a chemistry lesson. At the front of the room, the teacher practically did pirouettes in a dance of atomic models, electric charges, and absorption and emission spectra. At one point, he struck the board with a ruler in an effort to get the students' attention. The noise succeeded, but only for a few seconds, and he was unable to keep their interest or spark any excitement as he continued to plow doggedly through the rest of the lesson. About two minutes after the students had returned to their afternoon stupor, the sound of a rap song drifted through an open window from a passing car. Practically all the students sat up and almost simultaneously began nodding their heads to the beat. They looked up at one another and smiled. Some mouthed the words of the song under their breath, as they gave each other knowing glances that were acknowledged by slight head nods and brief eye contact. The song generated an obvious emotional energy in the classroom that the teacher's chemistry lesson could not evoke. As the car drove past, the sound of the song dissolved into muffled bass and a faint drum pattern, and its distinctive beat trickled into silence, replaced by the repetitive ticking of the clock at the front of the classroom. The teacher returned to his lesson, and the smiles that had filled the students' faces slowly melted into blank stares and looks of indifference, as they returned to their previous somnolence. This episode was just one of many surreal moments that drew me to explore the question of why urban students do not engage with science and what can be done about it. In each of my roles as teacher, administrator, and researcher in urban public schools, I have been struck by the magnitude of the separation between the culture of school science and that of urban students. Teachers seem to come from a world that is completely removed from that of the students, who seem to communicate in a kind of code that strengthens their connections to one another while it deepens their alienation from the world of science. In my research, I have found evidence of this separation by looking at students' scores on standardized tests, their lack of participation in science classrooms, and their decisions to choose careers far removed from the sciences. Consequently, one of the main foci of my work--and a theme that resonates throughout my dissertation--is the search for effective approaches to science instruction in urban schools that will allow students and teachers to have shared positive experiences about science. In order to fulfill this quest, I needed to understand that the powerful connection students have with their peers and their distinct cultural understandings (often expressed in music and in the ways they teach and learn from one another) are points of entry that educators and researchers must use to engage students in science. I also needed to understand that finding ways to bridge the cultural misalignments that divide school science and urban students would require both practical and theoretical innovation. By innovation here I mean a reinvention of age-old approaches to effective teaching that have been espoused by schools of education and constructivist educators and called a student-centered curriculum. What I sought to do was take the term student centered out of the realm of the ideal and beyond the language of cliche and deploy it for action to meet the needs of students in urban schools. In the paragraphs that follow, I will outline briefly what I call the three C's--a set of tools that can be used to improve urban science education--and describe the ways that they can support students who have traditionally been marginalized. …