This year marks 38 years since any part of the continental United States was darkened by the Moon's umbral shadow. During this "eclipse drought," no U.S. residents except those on Hawaii's Big Island in 1991 have had the opportunity to observe totality without traveling abroad. The 2017 Total Solar Eclipse (TSE2017, August 21, 2017) is also special in that the umbra (the Moon's shadow) travels the United States coast-to-coast, something that hasn't happened since 1918, and the Moon's umbral shadow does not fall on any other nation except the United States for the first time since we became a country--making this a truly Great American Eclipse. For those teachers and students fortunate enough to be within this path, daytime will turn briefly to deep twilight, the Sun's elusive corona (the plasma that surrounds the Sun and is visible during an eclipse) will come into view, and all the other phenomena that accompany this amazing spectacle will present a rare and unique teaching opportunity that, if properly prepared for and taught to full advantage, can promote scientific literacy in classrooms on a magnitude unmatched in the history of U.S. education.