Early readers with no real meat to them can be very difficult for competent readers to pass the "comprehension" tests on. We use a different levelling system but up to about level 15 (children move on to independent reading of chapter books 25-30ish) I myself often couldn't pass the "comprehension" questions without having another look at the book. Partly this is because when a book is that easy and that boring you don't retain a single word, which doesn't mean you didn't understand what you read... Partly because the "comprehension" questions often didn't even relate to the actual text and relied on having gazed in fascination at the pictures "What colour was mother bear's scarf?".
I have often thought that kids who don't start from "not reading" and learn HOW the teacher wants you to "read" the early readers and respond to the "comprehension" questions are at a distinct disadvantage when being assessed on books way below their level - because they are being tested on skills that they never learned because they never needed them, or they learned and have long since abandoned as no longer being necessary.
We are having a similar problem with math for eldest DD at the moment. She changed schools half way through grade 5 apparently her math skills plummetted... She's not amazing at maths, but she was well in the top 1/3 of her class (at a school with a much higher achieving cohort than her new school). But she has aspergers and has not been able to cope well with the different language used for math at her new school and that she is expected to do math calculations with different techniques. She has solidly above grade average math skills against one school's measure but not another's - because they have different ways of teaching and then measuring success for supposedly the same thing. If she had more flexibility of thinking this would have set her back less, but it is what it is...
