Just a thought: have you tried to determine whether it's the actual material or its presentation-- or even the environment?
Environment: Is he sensitive to sounds, smells, sensory stimuli in general? Is he distracted: by visuals, other children, etc. How does he generally handle sitting at a desk? Could there be anything about the classroom environment that distracts him?
Presentation: How would you rate his overall auditory processing/attention/learning? How does it compare to how he takes in info/processes info via other channels? Does he generally do better if he sees/reads material or if you tell him, read aloud, discuss it? Does he typically move around a lot while he's learning at home? Maybe try an experiment... Maybe he does hear blah blah when his teacher talks. Maybe he'd do better with visual presentation, or some hands-on, or kinesthetic experiences. Or maybe blah blah is a little boy describing his teacher (the charlie brown grown up talk version) or it's a cover for something else.
Anyway, could be many many things, but just wanted to toss these out there as a few possibilities.
Good luck!
