I’m curious as to why you “thought she would do better” and why you consider 2 different children having different scores to be a ‘discrepancy’. Kids aren’t made from cookie cutters. I have degrees from top 20 schools/800 standardized tests. Neither of my siblings went to college. My 2 kids are about 15 points apart - I work with both to maximize their potential. Human’s vary. Maybe it’s just me, but you questions sound like you’re asking how to ‘fix’ her.