Check out some of Silverman's Visual Spatial writings. From what I was told about my youngest dd, these types of kids can make very huge leaps in their abilities. They have many "peaks and valleys." This might be one reason for the later blooming.
This is currently true for my other dd, who tested extrememly high on IQ but just now has started to show her academic abilities with great leaps of growth. Her MAP scores have just jumped like crazy. She seems to be showing her Giftedness more each day and it's amazing to us how much different she is from Sept. until now.
