As teachers, we constantly and consistently need to update our course material and lesson plans to adapt to a changing world. Particularly if you are teaching technology-oriented subjects like I do. For the last 2 years I have kept an SD card with every single lesson plan for every class, and all of the course documents. (I'm not a big fan of paper). So my "folder" is my SD card. Because most of my classes are technology related, the market is constantly changing my classes. Software changes, new gear gets purchased, operating systems change, and some material become obsolete. I can only think of maybe 2-3 times where a class I taught did not change at all from one term to the next. I keep digital copies of everything because: (1) I can update the material whenever I need to, without retooling the lesson plan, (2) it saves paper [I just load the lesson plan on my laptop], (3) I can easily copy/paste material into an email or onto our student portal for students who missed class, and (4) it just makes my life because I save time on prep. However, at times I find myself falling into the trap of running on "auto-pilot." It's very easy to just work off of previous lesson plans and not incorporate anything new into my lessons. If I'm using a lesson plan that is 2 years old in a technology program, I'm not helping my students succeed the best I can. Fortunately, I have a day off every week so cab I devote time to update my lesson plans with new material every term -- even if updating a lesson is just looking it over, and making sure all the material is still relevant.