In recent years, student centered approaches to learning has gained interest especially STEM based learning. It has led to educational policy and standards reforms including the Next Generation Science Standards (NGSS), which helps teachers, incorporate Engineering and Technology into Science education. Generally, Engineering and Technology practices and principles are extrapolated from collegiate level to P-12 classrooms with limited understanding of what is developmentally appropriate for younger students. This research proposes a re-conceptualized approach to STEM integration using systems thinking that shows the natural connections between the individual subjects, Science, Technology, Engineering and Mathematics. The whole goal is to mimic not only the content knowledge, but also the skills and practices of the real world in P12 classrooms. This design research was conducted in a Grade 7 classroom of a suburban school. Analysis of student pre-interviews revealed that the students possess a rudimentary understanding of engineering thinking and parallel lines and lack a conceptual understanding of angles. These notions were used to design and develop mathematical instructional tasks with an engineering problem as the context in order to motivate students understanding to more sophisticated notions of angles and parallel lines. The post-interview analysis shows an improvement in the students’ understanding of angles, parallel lines and engineering thinking. The following STEM practices emerged from the classroom when the students engaged in the engineering based mathematical instructional sequences, (a) developing conceptual understanding in multiple subject areas; (b) building relationships among subject areas; (c) shifting back and forth between goals of the individual subject experts; (d) developing ethical thinking; and (e) rethinking communication.