Have you looked at the Iowa Acceleration Scale, mentioned above? I really think that this will clarify things for you. Also, what does your DS want? Does he want to skip?
DD9 makes silly mistakes when under-challenged, too. She can also get flustered when she doesn't immediately know the answer. IMO, these are NOT a good reasons to avoid the skip. In fact, I see these as signs that more challenge is needed.
Your DS sounds like he might be a deep thinker. This ABSOLUTELY does not mean that he is a poor candidate for being skipped.
