BOX 3.9 Eating Pie and Learning Fractions Even small differences in cultural knowledge have the potential to affect students' learning. For example, a primary school teacher is helping students to understand fractional parts by using what she thinks is a commonplace reference. "Today, we're going to talk about cutting up a Thanksgiving holiday favorite--pumpkin pie." She continues with an explanation of parts. Well into her discourse, a young African American boy, looking puzzled, asks, "What is pumpkin pie?" (Tate, 1994).      Most African Americans are likely to serve sweet potato pie for holiday dinners. In fact, one of the ways that African American parents explain pumpkin pie to their children is to say that it is something like sweet potato pie. For them, sweet potato pie is the common referent. Even the slight difference of being unfamiliar with pumpkin pie can serve as a source of interference for the student. Rather than be engaged actively in the lesson, he may have been preoccupied with trying to imagine pumpkin pie: What does it taste like? How does it smell? Is its texture chunky like apple or cherry pie? In the mind of a child, all of these questions can become more of the focus than the subject of fractions that the teacher is attempting to teach.