Recently, educators in public K-12 schools have added testing of science knowledge to the measures of Adequate Yearly Progress required by the federal No Child Left Behind (NCLB) legislation. Research of the impact of NCLB policy on general teaching practices had credited the policy with improving instruction; however, negative impacts noted included the concern that teachers "teach to the test," narrowing the curriculum. Testing as an assessment strategy was not advocated by the professional educators and scientists responsible for the National Science Education Standards (NSES). Results from previous studies pointed to a potential conflict between the NCLB reforms and the National Science Education Standards science standards, in which teachers might reduce or eliminate hands-on activities and other constructivist practices in order to focus class time on other topics and tasks. Most research on NCLB policy, however, had not evaluated instructional practices regarding science education. This study examined the relationship among teacher beliefs, specifically the strength of their constructivist versus traditional beliefs, teachers' responses to NCLB policy, and teachers' use of constructivist practices in the form of manipulatives. This study showed that national policy did have an impact on teachers; however, that impact was not specific to the hands-on practices in science education. Teachers who responded to this survey had found many benefits in student learning using manipulatives and those positive impacts on their students justified the increased use of manipulatives in the classroom. The strength of teachers' constructivist beliefs showed a weak positive correlation to choices related to curriculum priorities, learning goals and advantages in using manipulatives. However, a relationship to beliefs was not found in the changes teachers made to various instructional practices, or in how they viewed certain manipulative materials, or in how they viewed federal policies. The impact of the federal policies was related more to school climate and teacher motivation than instructional choices. Most teachers reported positive impacts on student learning using manipulatives and these results, more than the pressure they felt to "cover the curriculum" or prepare students for standardized tests, provided reasons to continue using the practice.