Step-by-step explanation:
The moon changing its shape from crest to full moon and again from full moon to crest or new moon is a natural phenomenon and it will provide the same result from any part of the world. Therefore the results of the four groups of students investigating the reason for the changing shape of the moon from different parts of the world is same and valid thy give the same result no matter from which part of the world we are observing the phenomenon. This is the law of nature and it will be the same at every part of the world.