This summer I learned about Doctopus from the great Kevin Brookhouser and that will probably change some of my workflow, but for those of you who aren't ready for that here are a few alternatives.
Step 1: Get Student Data
To share anything with students you need to know their gmail address. I highly recommend setting up a Google Form to gather this data. Here is an example of mine. Student Data Form.
Once you have student's information you can sort the spreadsheet by period, by name etc, copy the relevant email addresses, click the share button on any document, paste in a list of gmail addresses and you're off to the races. Great, but a bit tedious to have to do that copy and paste step every time you want to share something.
Step 2: Set Up View Only Folders
You probably noticed when you shared that document, that you had a choice about how you shared it, edit, view and comment, were probably the different options. Giving 36 students edit rights on a single document is a bad idea. Most often I share with students as "view only". A student who has view access to a doc can go to the file menu and "make a copy" of that document. The student will own the new copy. If your 36 students each make their own copy from a view only document then they just saved you a lot of time.
To make this even easier. I share a folder with each period called "View Only". Any document I put into that folder is automatically shared with all of the students and they can make their own copy to edit, annotate etc. I set up separate view only folders for each period because there are times when I want to share something with one class, but not another. I made you a short tutorial video about how to set up view only folders.
Step 3: Set Up Group Folders
Group folders let my students and I share documents with a smaller group. I use this mostly with writing groups. I share a folder with the 5-6 students in a writing group, but this time I give them edit access. (I might switch that to comment access since that is an option now.) Anything I or the students put into that folder is shared with the group. Students use this to share their writing with their group. It is much faster than them having to type in each group member's gmail address.
I create the heterogeneous groups using the spreadsheet, putting a group number next to each student's name. I sort by the numbers and then I have student emails by group. From there it just takes a few minutes per period to set up the folders and paste in the emails for each group. The prep time it takes me to do that is worth it because it saves my students time in class when they can share their work much more quickly.
File in More Than One Folder
You can still put a Google Doc in more than one folder. (I just found out lots of people thought this went away.) I use this trick to put the same document into the view only folder for each class.
Select the Doc in your docs list.
Pick the "organize" button. (looks like a folder).
Select the first folder you want to put it in then hold down the control key (or command on Mac) and click on all the other folders you want to have that doc go into. Viola, the document will appear in each of those folders. I use this trick when I want to add the same document to several view only folders at once.