Answer: No Child Left Behind Act.
Step-by-step explanation:
No Child Left Behind Act is the act that helps poor children through providing money for education assistance in exchange of student's progress in academic field.This federal law impacts student study, examination through test ,teachers training as well as spending of money on this project.
According to the question,No Child Left Behind Act is impacting decision of teacher as it is important for students to finish vocabulary study for test to gaining educational assistance .Thus, he stopped assignment of book.