This convergent mixed methods study sought to explore the effects of engineering design challenges (EDCs) on middle school students' achievement. Data was collected from four middle schools from an urban school district in Maryland. Two of these, Group A, included teachers with experience with EDC design and implementation; the other two schools, Group B, were used as comparison schools and it was assumed that they didn't have the expertise of Group A. Quantitative and qualitative data were collected regarding the four sample schools. Quantitative data consisted of Maryland Integrated Science Assessment (MISA) scores while qualitative data consisted of teachers' responses to survey questions. An EDC lesson plan or prompt from participants was then rated using a quantitative score in terms of motivating/ engaging students, involving the engineering design process, integration of science content, teamwork, and communication. Descriptive analysis was employed to evaluate the quality of EDCs for both groups. Results suggest that there was a statistically significant difference in MISA scores between Group A and Group B, with Group B scoring higher than Group A. Teacher survey responses and analysis of the EDC lesson plan/prompt suggest similarities for both groups in terms of frequency and quality of the EDCs, teacher understanding of the NGSS, three-dimensional science instruction, and EDCs. Future research is needed to explore the effects of the NGSS on science instruction and how to best meet the evolving demands of science instruction to ensure all students are equipped with the skills necessary to be scientifically literate. [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.]