Make a folder for each subject. Changing the color of the folder to match your class will make things easier. Put all of your folders for your classes inside a folder that is called the "6th-grade folder" "7th-grade folder" or "8th-grade folder". Also inside each of your class folders, be sure to add units for example in math if you are doing long division and you have a Google doc or slide, make a folder under the name "Long Division" and put the doc and slide in the folder. This will make things a lot easier.

If you have images or any other files that are not school-related and do not fit into any of your existing folders, make a folder under the name "images" or "Slides that I made for fun". This way you don't have any random files. If you also have any unnamed files, name them or delete them if necessary. 

If you have trouble figuring out which files you need or not, here are some tips. 

1. If you have files and Google Classroom folders from old grades, you should delete them unless a teacher told you not to for some reason. For example, I am in 6th grade and I have a bunch of files from 4th and 5th grade, I already know all the stuff they were teaching in that slide: then delete it. Most people have a bunch of slides that teachers used to teach you guys something you now already know, so deleting it is the best option.

2. Keep something if you need it even if it is from a previous grade. For example, let's say I was great at math but a bit rusty at science and I have a bunch of science slides from Elementary School that teach the stuff we are learning in science right now, the best move would be to keep the slide show. If you know a file is going to help you later on you should keep it. 

3. What about past projects and all? This part is a bit tricky, you should keep most of your middle school projects if not all. For Elementary School projects, deleting the ones that you don't want to keep or even your favorite pieces is an option since most Elementary Schools give out paper copies of projects too. This part depends on the person.

4. What about my free writing? Just like most people get rid of clothes they haven't worn for a year, free writing files have the same type of thing. If you haven't worked on a short story for 2-3 months, you should delete it. Again, this part depends on the person.