This project team will develop and test a prototype of Descartes, an online game and simulation platform for design-to-build engineering projects for students in grades 4 to 7. The prototype will include a virtual workspace for students to create and test models. Students will apply learning to design a boat using engineering principles, and the prototype will incorporate a 3D printer to create a physical representation of a simulated model. In a pilot study with three grade 5 or 6 classrooms, the researchers will examine whether the prototype functions as planned, whether teachers believe the prototype can be implemented in a classroom setting, and whether students are engaged while using the prototype.