I was posting before about how DS6 had been assessed by his school as reading at a mid year 1 level while a privately administered WIAT abbreviated had him hitting the ceiling with at least a year 3 level. As part of his most recent assessment he was administered the WJ-iii ach test and the report says his reading performance is at about a year 5 level and his comprehension at a year 4 level, which seems consistent with the WIAT results. I still find this gap between the school's assessment and the private assessments to be quite dramatic.
Sometimes I find it hard to get my head around what level DS is actually achieving and what his needs are that I need to be advocating for.