Engineering Design (ED) challenges are increasingly used as a context to learn science. Research shows that there is a need for strategies that facilitate learners to identify, apply, and reflect on ways scientific principles can inform creation and evaluation of ED solutions. We investigate the use of contrasting cases and argumentation scaffolds to facilitate use of evidence-based reasoning in a CAD supported ED tasks. Elementary education majors in a physics course analyzed solutions to an ED problem in two conditions: 1) identify similarities and differences, 2) evaluate and produce an argument for a “good” design solution. We found that the argumentation condition used scientific evidence-based reasoning significantly more frequently in their responses than the control. Results indicate that the contrasting cases with argumentation scaffolds shows promise in facilitating students’ use of evidence-based reasoning in their ED tasks.