I posted a Word.docx file to the course page but some people can’t open it.
This is a compatibility issue. Microsoft Office 2007 files have an extra x on the end of the extension, so a Word.doc will look like Word.docx if you are using Word 2007. People who have older Word versions, will not be able to open these files. This can be fixed two ways:
You can re-save your document as an older version. For example in Word, go to save as and select save as a .doc file.
People who have the older Microsoft Office can download a pack from Microsoft. This will enable them to open any 2007 Microsoft Office documents such as Word, Power Point or Excel. The pack can be downloaded at this URL:
If you are an instructor, you can post this link on your Moodle site.