To the whole class I said "Now is the time to get out your agenda and write the homework."
And she did it. She put down her drawing. She walked to her backpack, pulled out her agenda, found a closer spot and WROTE HER HOMEWORK (on the right day and not in marker!) She then took the homework out of her desk, put it INSIDE of her agenda, closed it and put in back in her backpack.
Now to get her to bring it back. Baby steps.