That is the kind of result that has potential significance. A two standard deviation difference between VCI and word attack occurs pretty infrequently.
No, you do not need a formal assessment before using AAR or AAS. Use the placement materials from the curriculum (freely downloadable on the AAL website). I would be hesitant about skipping levels altogether, though, as there may be hidden skill deficits. He probably will swing between blazing through sections he already knows, and stopping at new skills. When you do a lesson, if he clearly has already mastered the skill, then do the teaching, but don't bother with the practice. Have him teach the skill back to you to check for comprehension, and move on to the next lesson. If you spot him a lead of a few weeks, you can probably get him far enough ahead of LB that they won't be doing the same lessons. It may also help to remember that AAR is not based on grade levels. It's four levels that are supposed to take the learner through late middle-school/high-school level decoding skills. So being in Level 1 does not necessarily mean 1st grade skills.
