Echo what Kim said and add:

Is it discussion questions? I always write discussion questions, but if I teach even I don't follow my own curriculum word for word. Otherwise, it's a stilted lesson.

Inviting these teachers to be part of curriculum development gives them a voice. The curriculum development can be a fun, creative process and maybe they feel left out.

Honestly reflect on the curriculum you presented. Did it need extra activity? Was it over the kid's heads? Was it too difficult for the time allotted? Was it taking too strong a theological position?

I usually include at the end of our curriculum a few notes:
(1) If time runs short
(2) If you have extra time
(3) Adjustments for age levels and abilities (4) Be creative...
Each includes a few notes. Not sure if that helps them find ways to be creative within the given lesson plan, but I have seen them use these options.

Peace,
Lisa