Just a thought. My sons also have low processing speeds. One day my youngest was working on the computer he turned and asked me why the easy questions are hard and the hard questions are easy.
I feel once they have mastered the easy stuff their brains move to the next more interesting harder stuff. Now that their brains are fixed onto more complicated material, it's hard for them to back step. Which requires them to stop and think. Hope this makes since to someone.
Kind of like walking. It's easier to walk forward than it is to walk backwards.
