The zone of proximal development, often abbreviated as ZPD, is the difference between what a learner can do without help and what he or she cannot do. It is a concept introduced, yet not fully developed, by Soviet psychologist Lev Vygotsky (1896â1934) during the last ten years of his life.
Report Abuse. 1  Baguio City Elevation. 2  The city is at an altitude of approximately 1500 meters (5100 ft) in a moist tropical pine forest conducive to the growth of mossy plants and orchids. 3  It is over 5,00Today: Cloudy with showers.  try yahoo weather.
Once Phobos gets down to an altitude of only 7000 km above the center of Mars (or 3,620 km above its surface), it will enter whatâs known as the Roche limit. At this point, the tidal forces of Mars will tear Phobos apart, turning it into a ring that will continue to spiral into Mars.