Let them dream hard!
Imagination doesn't come alone... Also for us, adults.
To activate our inner power of creation, we need to settle a peaceful environment, to choose an adequat moment, to know that there is no pressure for us and no need to be available for anyone at this very moment. Well, that's exactly the same process for our children... Let them get bored, let them go around in circles in their jar, grumbling. It's when you're past the stage of occupational research that you reach the perfect state of mind to make EXPERIENCES!