Ask "why" until you hit a dead end. The dead end will guide inquiry-based learning and help students identify their own areas of curiosity. This idea is informed by the "5 Whys" Questioning Method by Sakichi Toyoda and varies only slightly in that it's not necessarily the minimum number of 5 questions for kids, but until they can't go further in their Q&A. Depending on the depth of knowledge and understanding, students will get "stuck" earlier or later in the process. Again, this isn't an original idea or method, but one that I strive to keep visible for learners in some embedded way. I want to build it into the design process for my students...just not sure exactly how or where I'll do it.