After the engineer has proposed a good design solution, the next step is to test and analyze that solution in order to verify that it is a good, viable, workable solution, and to make sure that it meets all the design constraints. For example, after an engineer has proposed the design solution for a bridge, he may want to analyze the bridge to make sure that it can actually hold the weight that it was designed to hold. Another great source of analysis that engineers use is the colleagues and co-workers. By presenting, talking, and demonstrating their design ideas to a group of colleagues, an engineer will gain a deeper understand and insight to the problem. In doing this, problems may arise that were not thought of before when developing the success criteria. It is at this point where the engineer may need to go back to other steps and refine the problem statement or the design criteria. (S)He may need to do some more research and investigation and/or (s)he will then need to propose new/refine the design.
Working with classmates as colleagues, students will analyze and evaluate all the potential design solutions. Solutions may require further testing and experimentation to meet the criteria for success defined previously, and even the criteria for success may need to be amended. This step may include students checking their results with other sources of information (such as other students and teachers, or other designs that were discovered in the "Research and Investigate" step of the EDP) and make connections between their results, scientific knowledge, and engineering design.