The goal of this study was to document one teacher’s implementation of three different engineering design-based science units and his students’ learning and interest development after engaging in these units. The analysis of student content test data demonstrated that at the end of each unit the students gained science and engineering knowledge. However, there were only statistical differences in student learning between the first year and the third year. Students who participated in the study in year 3 demonstrated larger knowledge gains compared to students in year 1. In addition, students developed an interest in science and engineering as the result of engaging in engineering instruction as reflected in the pre-test to post-test change. In other words, student participation in engineering-focused science units had an impact on their interest development. This finding supports research indicating that engineering activities enhance student interest in STEM (High, Thomas & Redmond, 2010; Lachapelle & Cunningham, 2014). However, there was no statistical difference in interest development between the students in years 1, 2, and 3. One possible explanation for this finding is that each unit and enactment has the same degree of influence on student interest. Research has shown that when students are exposed to engineering they are more likely to become interested in this topic, though not all students respond the same way to engineering interventions (NAE & NRC, 2009). For example, our results showed an increase in interest among female and male students, but female students’ interest rose more. An investigation of why the participation in the third year unit, explicit integration, did not show a greater increase in interest among students would be informative. The analysis of videotaped instruction demonstrated some differences between the implementation of the three units that could be linked to the differences in student learning. First, the sequence of science and engineering activities fell into three patterns: (a) add-on in year 1, (b) implicit integration in year 2, and (c) explicit integration in year 3. In year 1, science and engineering concepts were not closely connected as Mr. Smith tended to separate the science and engineering activities. However, science and engineering activities were interwoven in year 3. Second, Mr. Smith’s talk introducing science and engineering fell into two patterns: (a) focusing on distinct or unique characteristics of science and engineering in brief and isolated discussions in years 1 and 2, but richer and more scaffolded discussions in year 3; and (b) identifying students as “engineers,” the client as the “decision-maker,” and himself as the “mediator” in between the two in years 1–3. Looking across the practices of Mr. Smith, when and to what extent students engaged in engineering practices and discourse in science classes seemed to result in knowledge gain differences between the three groups of students.
It is important to note that the presence of Mr. Smith in each of the classrooms in this study likely means that some student scores on the post-tests were correlated, which could distort the statistical results to some degree. Although the findings of this study are confined by the limitations of a single teacher, the analysis finely illustrates the ways Mr. Smith integrated engineering and life science content and the ways he talked about engineering. The study also shows what effects these strategies had on student learning and interest development. Naturally, the results of this study cannot be generalized to all middle school science classrooms; however, the results provide evidence of ways engineering can be integrated in science classrooms similar to those in the study. The use of qualitative and quantitative data helped to better understand differences and similarities of engineering integration each year and the influences of those strategies on student learning. However, the study design and a single teacher participant do not support making casual connections between teacher practices and student learning. Finally, our results suggest the need for additional research on engineering integration in science. This includes exploring the engineering challenges students are tasked with in other science content areas, engineering discourse students engage in, and the effects this discourse has on students’ learning and interest. A comparison study can shed new light on the differences in the science and engineering learning and discourse in different science content areas.