At least that is what our governmental administrators and legislatures are saying, and no doubt that is the belief of the general populace.
The U.S. ranks 33rd in National Test Scores out of the 172 countries in the world. However, when you compare the test scores to other countries that believe all students should receive a free public education. (Oh, none of the other countries that score higher than us educate the entire populace). The exceptions are countries i.e. Norway, Sweden, Denmark, which have a population about the same as Montana with no diversity.