Structure of the Earth easily than does the upper mantle (chemical changes within the mantle may also be important). The viscosity of the mantle ranges between 10 and 10 Pa·s, depending on depth. In comparison, the viscosity of water is approximately 10 Pa·s and that of pitch is 10 Pa·s. The source of heat that drives plate tectonics is the primordial heat left over from the planet’s formation as well as the radioactive decay of uranium, thorium, and potassium in Earth’s crust and mantle. The average density of Earth is . Because the average density of surface material is only around , we must
Science of Education: Its General Principles Deduced from its Aim and the Aesthetic Revelation of the World Science of Education: Its General Principles Deduced from its Aim and the Aesthetic Revelation of the World Science of Education (full title: Science of Education: Its General Principles Deduced from its Aim and the Aesthetic Revelation of the World) is a book written by the German empiricist Johann Friedrich Herbart. It was first published in German in 1806 and the first English printing was in 1902. Herbart emphasized education as the way for an individual to fulfill his potential and created a scientific method to help him do so. The Science of Education advocated a five-step methodology that appeals to