The US Census is designed primarily to identity vital statistics about people in the US. They're interested in information like: your date of birth, your race, your gender, where you're currently physically located, your heritage, the language(s) you speak, the number of people in your family, your general financial status, and whether you own or rent.
The Census does not ask questions about your future plans of cooperation or non-cooperation.
The Census does not 'test' how well a person knows about other cultures; it just wants to know about you, your family, and your background.
A lot of schools in the United States specifically make a point not to inquire about the immigration status of students precisely because they are in the business of helping children learn and the immigration status (or lack thereof) of the parents, if used as a criteria for student enrollment, might deter parents from enrolling students.
Therefore, as the others have stated, the best answer would be that teachers are going to need increased training in cultural and linguistic differences, or B. The trends of the Census include an increase in the non-native English speakers and those who do not have a solid grasp on the English language. Also among the trends is one that indicates a rise in the number of immigrants, legal and otherwise, including children in need of (preschool) education.