Maybe I could have him take the 5th grade assessment to see how he does there as well - it seems to me that if he knows 90% of the 4th grade material and some healthy amount of 5th grade, that would be convincing...
Even if you are already using ALEKS, be sure to sign up for a separate free trial so that the Assessment does not factor in anything he's mastered while using it for 4th.
Unless the school is familiar with ALEKS, I doubt they'll give the assessments much weight, especially as they can't see the contents or results of the assessments. BUT... (hopefully!) they should allow your son to take whatever end-of-year test you think he's ready to tackle.
You should also build into your conversations *now* the idea that depending on the outcome of their testing, he should only have to repeat the specific sections for which he demonstrates a weakness, if at all.
When our son scored >90% on the 4th grade "final" the school uses as a pre-test at the start of the year, his teacher locked onto the couple areas of weakness and tried to say that the whole course should be repeated. (Never mind that kids were allowed to progress naturally from 4th to 5th with far less proficiency...)
We finally agreed on having our son review the specific sections when the class reached them in the book, but that he'd be allowed to proceed on his own in ALEKS for 5th.
To our son's credit, he never had to review those sections because he finished 5th grade on ALEKS in 4 or 5 weeks -- and then scored >95% on the school's
expanded final for 5th grade math.
