Google Scholar is a search engine for scholarly information such as:
When you do a search in Google Scholar, you get a list of citations. You'll get links to the full text in the following cases:
This is how Google Scholar defines their weighting system (the value given to each search result, depending how important or significant it is):
"Google Scholar aims to rank documents the way researchers do, weighing the full text of each document, where it was published, who it was written by, as well as how often and how recently it has been cited in other scholarly literature."
Remember, Google's goal is to make the world of information accessible and useful. It is still up to you, as a responsible student, to critically evaluate research materials.