Explore and apply: Instructional design should involve labs in which students first explore a concept by studying the relationships between causes and effects (Marek, Maier, and McCann 2008). Once students have developed an understanding of how important variables affect an experimental situation, they can be challenged to use the engineering model and apply their newly formed conceptual understanding to generate a product or maximize an output. In this manner, the science model is employed early on in the exploration phase of the lesson, and the engineering model is used in a subsequent phase of the lesson as an application of student understanding.
I am going to try to add this distinction into my inquiry design. I find that is tend towards engineering experiments in physics class because the have definite easy to describe goals. Even if I design the inquiry around a big engineering question I should always ask myself: where in this unit is the science inquiry? The whole article is worth a read, sorry it is not free on the internet. Have you found any other useful distinctions between science and engineering? Do you have a checklist of that you go through when designing an inquiry?