Answer:

1. because with one straight edge, the pieces are easier to identify and put together. “There isn't a single strategy that will work for 100 percent of puzzles, but in the majority of cases, it is easiest to start with the edge,”
2. you just pick up a handful of pieces. And then you go through it and you put all of the inside pieces in the big box and you put all of the edge.
3. Fossils of similar organisms across widely disparate continents encouraged the revolutionary theory of continental drift, Continental drift describes one of the earliest ways geologists thought continents moved over time.

crdts:ggle