How could someone reconstruct Pangaea?

They could in a model. However, they could not actually reconstruct the earth or another planet to look like Pangea. A cool experiment to do to demonstrate how the continents broke apart due to plate techtonics, make a hard-boiled egg, and draw a circle on the shell. Cut the shell (not the egg) into the circle, but do not remove the circle. Place your thumb on the circle, and move it around on the shell. This will show you how the land broke apart into smaller chunks and islands. you can also eat the egg afterwards! :)