As an extra credit, : Must discuss at least one (1) other student's topic Student discussion: Since  its emergence in the 1960's, plate tectonic theory has gained  wide-spread acceptance as the model of how Earth's land masses shift  over time. Plate tectonics developed historically in 1915 when Alfred Wegener proposed his theory of  "continental drift." He stated that the continents plowed through crust  of ocean basins, which would explain why the outlines of many  coastlines, such as South America and Africa, appeared to fit like  missing pieces of a jigsaw puzzle.  There  are various types of plate boundaries such as: convergent plate  boundaries, when two collide; divergent plate boundaries, when they  spread apart; and transform boundaries, when they slide past each other. http://scecinfo.usc.edu/education/k12/learn/plate2.htm .

1. As an extra credit,
:
Must discuss at least one (1) other student's topic
Student discussion:
Since its emergence in the 1960's, plate tectonic theory has
gained wide-spread acceptance as the model of how Earth's
land masses shift over time. Plate tectonics developed
historically in 1915 when Alfred Wegener proposed
his theory of "continental drift." He stated that the continents
plowed through crust of ocean basins, which would explain
why the outlines of many coastlines, such as South America
and Africa, appeared to fit like missing pieces of a jigsaw
puzzle.
There are various types of plate boundaries such as: convergent
plate boundaries, when two collide; divergent plate boundaries,
when they spread apart; and transform boundaries, when they
slide past each other.
http://scecinfo.usc.edu/education/k12/learn/plate2.htm