I started by sorting out the worksheets from the artwork. That got the pile down quite a bit. Then I started looking at their artwork and thinking what was best to save and which pieces I wasn't as attached to. Again, that helped cut the piles in half (almost). It's still a lot, but it's far more manageable.
Now then, I needed to find a way to store those treasures nicely. Good old Pinterest to the rescue. I found pretty labels, just the right kind of art box to store things in and a way to organize memories & school photos. Awesome!