Of the three major minority groups, two always post scores substantially lower than the third and the white majority, and most States (Vermont is a nearly unique exception in this respect) have substantial minority enrollments; this fact therefore produces total averages noticeably lower than the one or two which don't.
All these achievement-by-demographic-cohort stats, for each state, are published in the annual National Digest of Educational Statistics, which you can request (usually no charge) from your favorite Congressional politician's office.
There you'll find, for fourth grade reading, that statistically all-white Vermont posts a student test score of 229, while the U.S. average for the white cohort is 230. And how "high value" is a 229 score? Hint: it's less than halfway up the 0-500 score scale.
When Vermont claims, on the basis of state total-enrollment averages, to have the best schools in the K-12 neighborhood that's because the overall neighborhood isn't even middle-class (pun intended) achievement-wise.
The states at the bottom of the heap spending-wise get there primarily via larger class sizes. Utah, for example, has an average class size twice that of Vermont's and a cost-of-direct instruction half as much per pupil. All the others are similarly more efficient than Vermont-class-size and instruction-cost-wise-and controlling for the test-score depressing effect of their minority enrollments, they all post reading scores quite close to those of the Education State.
Here they are, for white fourth graders in 2007: Idaho 223, Mississippi 208, Tennessee 216, Utah 221. These four average at 217, 12 below Vermont-that's 5 percent.
The per-pupil spending of the four states is about 50 percent below Vermont's. The four states also post eighth grade reading proficiency percentages in the three-out-of-10 range-meaning that in the four low-cost states, seven out of ten students can't function at grade level in reading.
In high-cost Vermont, the proficiency rate was 42 percent, meaning that almost six out of ten were sub-proficient in eighth grade reading.