Off the top of my head: could be a breadth/depth thing, could be that the books are a union of California and Texas (in which case CA and TX also have the probl

Off the top of my head: could be a breadth/depth thing, could be that the books are a union of California and Texas (in which case CA and TX also have the problem of unused chapters), or it could be that the time not spent on those chapters is spent on something that MN brings in with supplemental reading already or just teaches without a textbook. It almost certainly isn't just that MN is a simple subset of the CA/TX material, or else the Byron district's scores wouldn't have gone up from the new material.