I'm writing up research we did on the impact of our masters degree program in arts integration and one thing that really strikes me is that the aha's seem to come from engagement in the creative process.  It doesn't seem to matter so much whether it was drama or poetry or movement (though each discipline clearly provides access in a different way). The realizations connected to the way teacher's think about the curriculum in the udl frame of representation, expression and engagement, seem to come from going through the process of making, translating, and sharing and having the opportunity to move through this process in different ways again and again.

We do see that teachers need time and space and many opportunities to develop their sense of creativity because many teachers have experienced a paralyzing moment earlier on in life which makes them question their own creativity.