Is there a school psych? If so see if she/he can go into the classroom and do an observation. I actually went into the first grade class and watched as well for about an hour and was surprised at what I saw because DS was very off-task there and he's not usually that bad at home. However even with that I couldn't figure out if he just didn't WANT to do the work, if he couldn't figure out what to do, or if he was distracted by what was going on in the room. He was just sitting there staring off and looked a bit irritated. Then the school psych went in and observed while he was dong a paper-pencil math test and said he was on-task 49 percent of the time and it should be more like 80 for a first grader. When he wasn't doing the work he was looking out the window, playing with his eraser, etc. I STILL am not sure if this is ADHD or if this is DS being lazy or dysgrapic or fatigued from writing so much. It can be really hard to figure it out.

On the other hand, how old is your DS? If he has separation anxiety it does sound like anxiety is a huge issue. He could be off-task because he's worried about things that other kids wouldn't be worried about. I can see separation anxiety in terms of a 6+ year old not wanting to be dropped off at a camp without having friends there, or starting a new school, but what you describe about not wanting to be left alone in the living room while you're in the bathroom seems really severe. If he's worried about where you are in the house, and what's going to happen when he's alone, then he's not focused on what he's doing and will look spacey.