Next Generation Science Standards (NGSS) were developed by 26 lead states with NSTA, AAAS, NRC, and Achieve in 2013 to provide a new vision for the teaching of science in U.S. schools. Teachers' applications have been mainly concentrated on efforts to align the current practices with the standards. Elementary science teachers need to use instructional practices that integrate the three dimensions: Science and Engineering Practices, Disciplinary Core Ideas, and Cross Cutting Concepts to successfully teach NGSS. The purpose of this exploratory qualitative study was to better understand how elementary teachers use pedagogical content knowledge and curricular knowledge to choose and implement instructional practices that integrate the three dimensions of NGSS when teaching science at American private schools in the United Arab Emirates (UAE). Interviews were conducted with 10 teachers who worked as elementary science teachers at American private schools in the UAE. Classroom observations and lesson plans examinations were used to triangulate data. There were multiple coding cycles with codes derived from the two research questions. NVivo was used to categorize data and generate four themes. Findings showed that participants' views were aligned with the NGSS reforms and that they had used more inquiry-based, student-centered instructional practices. However, participants did not deliver three-dimensional instruction due to a disconnect between their perceptions and the requirements of the standards. This study supports positive change by providing knowledge on how teachers implement the three dimensions of NGSS. Stakeholders may be able to use the study findings to determine what training and professional development courses are needed and to construct better policies pertaining to the quality of teaching materials. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]