It's a two-step backsave.
Step 1 -- backsave in CC 2014 to CC 2012, and open in CC 2012
Step 2 -- backsave in CC 2012 to CS6
Know that NONE of the features exclusive to the more recent version will be backsaved into the earlier version.
If the school is renting Creative Cloud, it has access to, can download and install the 2012 version. But will it? Ah, there's the rub.......
Well we can probably get it on one computer if that is the case. I work their, as long as we have a reason we can download it, we recently had to go back to CS6 because our iMacs cant handle PS CC, 4GB is not enough RAM.
I realize this is an old post, but I'm trying to do the same thing (down save from CC 1014 to CS6) and I can't, for the life of me, find AE CC 2012 version as download on the cloud. Any tips on how to download the sucker?