It is interesting that school rewards certainty even though most amazing discoveries were a product of curiosity. As I science teacher, I speak of curiosity, read about it as a desired attitude in curiculum documents, and wish my students had more of it. But it is hard to measure, and things that are hard to measure in education tend to get ignored. Sure, it's a nice trimming to hope for in your students, but should it not be the linchpin of my teaching?
I do not think you can teach curiosity, but I believe you can inspire it in others. Afterall, we are born curious and so we all have it in us somewhere. So I try to live curiously, aloud, in front of my students and hope they catch on. Modeling.....it's the best tool in the teacher tool kit.