I have been encouraging students to understand the difference between simply clicking the 'X' to 'Close' their documents and verifying that they have 'Saved' their document first. We talk about who the 'boss' is of the computer. Do you want the computer to decide where your project is being saved or are you going to tell the computer where you want to find your project/document. We have also been talking about using shortcuts and how they can save you time if you have taken steps to find your project or document first.
I wasn't able to find a poster demonstrating the minimize button, so I made this one!