She says DS has a short attention span (~20 mins) and tunes her out sometimes when she's teaching. When he's spacing out he fails to get his books out and move on to the next activity, so he is also disorganized.
I would ask the teacher to clarify what she means by "disorganization". From your description the most likely explanation is that he's not engaged in learning so he spaces out (perhaps due to too much repetition or already knowing the material). To me, examples of disorganization would be misplacing things, not remembering to bring assignments back to school because they weren't put in his folder, poor time management, etc.
