XML document?

Does anyone know how to open this type of document? Last night I tried to open a document from our school's Microsoft Outlook and was unsuccessful. (This is a school document I placed on Microsoft Outlook hoping to finish at home) When I double-clicked the document it asked me to "open it" or "save" it. I saved it first to my documents and then went from there. When I opened it, the information was in 4 small folders "-rels," "docProps," "word" and (content types)- the type was XML document. I google it, and it said to try opening it up in FIREFOX browser, which didn't work. In addition, the information about the file read that it was a compressed zipped drive. In any event, I wasn't able to open the document and still after much research - I don't have a clear understanding of why it was a compressed zip file much less how to open one.