I have a confession to make...
I CANNOT stop buying books at the thrift store. My store has books for $.20 a piece and $3.00 a bag sales about once a month. So...I keep them organized by splitting them into categories and keeping them somewhat sorted on the shelves.
The shelf shown is for school books only and the books are sorted by Art/Practical Life/Sensorial, Science, Math/Language, and Geography. I even had a shelf left for our anatomy and leaf puzzles.
Now our normal day to day books are another story and are a huge mess!