I then include them in their developmental planning. During follow up coaching, I can then ask which of the items they have chosen that they have tried. The concept is interesting and well-formed, but in order to earn better than a 'C,' the idea must be feasible. A Yale university management professor, responding to Fred Smith's paper proposing reliable overnight delivery service. Smith went on to found Federal Express.
Creativity is pretty simple.
All you need to do is open your mind to new ideas. Unfortunately, opening one's mind is not a natural reaction any more, and not easy to do. Yet not long ago, engineers from a large automotive supply company did just that. They drove across the country without steering the car. Of course they had some help.