I have a love of books so to get rid of books is almost painful for me. But we all know that at the end of the school year you have to part with something to make room and money for the new stuff that will be coming soon.
I started with the curriculum books and purged the ones we don't need again.
If you have an Ikea close by, I highly recommend these magazine boxes. They're are cheap! Sure, they're not the sturdiest boxes, but they keep things organized, make your bookshelf look perfect and you spend less time trying to find a book. I started off thinking I could organize by subject but quickly realized that even within those subjects, I had too many books and needed subcategories. For example, for history, there is Pilgrims, Native Americans, Maps, World History, etc.
Sounds great, but you're asking yourself, "Where do I begin?"
Collect all books that you use for school. I keep picture books and readers separate on a bookshelf that they kids can access easily. This is JUST teacher materials. Look everywhere. Make sure you are thorough and look in every closet, under every bed and even in your car.
Now that you are buried in a stack of books taller than your refrigerator, it's time to start the analyzing process.
If you've ever watched the organizing shows on TV, you will be somewhat familiar with this process.
Touch each book. Look at it. Ask yourself if you are keeping it, selling/donating it, or it needs to be returned to someone.
Make stacks according to each of these categories.
The biggest mistake people make when trying to organize is that they go out and buy a whole bunch of organizing bins and baskets and then try to make their stuff fit in those. What you should do is look at what you plan on keeping and then set up a system that works for YOU. If you choose to use the magazine boxes like I did, each box holds about 5" of books.
Sort your books according to what works for you. That could mean sorting by grade level, subject area, publisher, or child.
Whatever you choose, make sure it is not too complicated or you will have wasted your time and money on a system that won't function.
The Ikea Magazine holders were perfect for me and all the teaching materials I've accumulated from being a public school teacher.
Another great container are these boxes that have handles on the lid.