The education literature contains many studies of what happens in schools and classrooms, but no documentation of what actually happens to children during an entire school day in a nationally-representative sample of students in the US. This study presents data collected from a nationally-representative sample of teachers of first through fifth graders (N = 553). Teachers completed a time diary, recording exact beginning and ending times for all the target student's school activities for a randomly selected day. We examined students' total time in school and their activities while there. We found wide variation in the length of the school day based on the student and classroom characteristics. Students attending school for the longest day were significantly more likely to be White and have fewer special needs, and to have smaller classes with a larger percentage of White students and a smaller percentage of students of other races than students attending for less time daily. We grouped students' activities at school into four categories that accounted for all but 9 minutes of the school day: academic, enrichment, recess, and maintenance activities. We found variations in how students spent their time based on student, family, and classroom characteristics. Teachers of African American students reported spending more time on academic subjects, and less time on enrichment and recess activities than teachers of white students. The same pattern emerged for teachers of more advantaged students, and classrooms with a larger percentage of White students. Results are discussed in terms of school reform efforts and inequality issues.