What is the best description and use for Google Scholar in a classroom?

An online thesaurus that finds definitions and provides examples of how to use words in sentences, to help improve writing queality.
A useful Search tool to find academic or scholarly sources, for research purposes and citation within original work.
A curated reading list based on a specified topic and grade level, for students to find additional information outside of the class text.
A chat tool that links students with other students to provide peer support and answer questions on a particular topic.