δ-ferrite is stable only at relatively high temperatures.

The relative decline of American education at the elementary- and high-school levels has long been a national embarrassment as well as a threat to the nation&39;s future. Once upon a time, American students tested better than any other students in the world. Now, ranked against European schoolchildren, America does about as well as Lithuania, behind at least 10 other nations.

For much of this time—roughly the last half century—professional educators believed that if they could only find the right pedagogy, the right method of instruction, all would be well. They tried New Math, open classrooms, Whole Language—but nothing seemed to achieve significant or lasting improvements.

Yet in recent years researchers have discovered something that may seem obvious, but for many reasons was overlooked or denied. What really makes a difference, what matters more than the class size or the textbook, the teaching method or the technology, or even the curriculum, is the quality of the teacher. Much of the ability to teach is innate—an ability to inspire young minds as well as control unruly classrooms that some people instinctively possess (and some people definitely do not). Teaching can be taught, to some degree, but not the way many graduate schools of education do it, with a lot of insipid or marginally relevant theorizing and pedagogy. In any case the research shows that within about five years, you can generally tell who is a good teacher and who is not.

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