This STEM education unit of work occurred at the beginning of a three-year longitudinal study titled Developing Engineering Education in Primary (DEEP) for grades 4- 6. There were five schools involved with a total of 10 classes and 270 year 4 students. This paper reports on findings from one year 4 class comprised of 19 girls. The engineering education program was divided into two parts with approximately two and a half hours allocated for each part. Part 1 focused on developing science and mathematics concepts assigned to the engineering activity: Engineers working with materials; the problem (design, make and test a medical mission kit); exploring 3D shapes; temperature; states of matter; testing the properties of materials. Part 2 focused on the engineering activity: The problem and discussing resources; designing and making the medical mission kit; testing the covering of the medical kit design; discussions during testing; recording results; testing the strength of the medical kit design; evaluation and redesign; and feedback on the activity.