In this video Paul Andersen explains how many possible solutions are developed in the design process. As many solutions to the problem are identified using a brainstorming process. These solutions are compared to the specific constraints and criteria of the solution. Models are created to test the viability of each solution. A K-12 teaching progression is also included.
https://thewonderofscience.com/videos/2017/12/10/ets1b-developing-possible-solutions