I'm the ALEKS administrator for my school and I'm not sure what you mean by "going along with the class." Unless the teacher is manually resetting ALEKS, this just doesn't happen. Your DS would take an assessment at the beginning of logging into ALEKS the first time. From that assessment, the software fills in a pie based on what he already knows, needs to know or wasn't tested.
Once a child has completed 85% of the pie (unless the school set it lower) then the teacher receives an email from ALEKS saying it's time to move to the next level, where the whole assessment starts over again for the new grade/course.
If he hypothetically completed 85% of 6th grade and the teacher re-placed him in 6th grade again, he'd take an assessment. If he finished 85% or close to it, ALEKS would email again saying the child is ready to move up.
It sounds like based on your explanation that he maybe needs to move to the next class? But I'm still not sure how he has anything left to do in ALEKS and the teacher didn't reassign him.
I think DS took an assessment in the beginning. Should the Aleks people be able to look up the assessment? He has put 2 hrs on the program and it looks like he has 50% of the pie complete. DS mentioned being frustrated because he said the program thinks he doesn't know division. I'm not sure what to think, but if the teacher does not support the program, we can't get anywhere.
At home,DS took an assessment on line from
http://www.tenmarks.com/asdoAssessmentInit.action and scored 85% on 5th grade math, but they thought it might not be higher level thinking. He is at a GT school. I think there were 20 questions.
The whole idea was that he would do Aleks so his pace would be more appropriate. It seems he is stuck doing the regular class work at a too slow pace, going along with the class.
The only other solution I can think of is if he had indivual help from another teacher/tudor. I don't think they have the resources for this.