Students' science achievement has been subject to scrutiny and criticism in the United States. The decline in rankings on standardized international assessments has been the focus of concern for educators, policy makers, parents and society at large. This study, designed as an action research, explored the factors contributing to the decrease in the number of students attaining advanced proficiency in science learning as measured by state assessments in grades four and eight in a New Jersey school district. Specifically, this study addressed the degree to which the middle school curriculum reflected the national science framework standards for 21st century leaning and the New Jersey Core Curriculum Content Standards; the pedagogical approaches regularly planned and implemented in the middle school science classrooms; and the students' perceptions of their science learning. Research data were collected by teacher and student surveys, focus group discussions, student interviews, document reviews of written curricula, and classroom observations. An important disparity emerged between the document analysis of the local curriculum and the teachers' views that 21st century learning skills are reflected in the written curriculum and classroom pedagogy. Further, classroom observations revealed the prevalence of a traditional pedagogy, focused on repetition of teacher-disseminated information and featuring limited differentiation, inquiry-based or constructivist learning strategies. The students expressed a value for discovery and collaboration with peers in order to develop, share and refine their understanding of science. The research concluded with recommendations for a revised curriculum process, sustained and collaborative professional development, on-going formative assessments of student learning and the formal integration of an online student science blog as a means of encouraging the co-construction of deep and enduring science knowledge. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]