For the families that use paper-bound workbooks or worktexts, try this:
Go to your local copy place and politely ask them to cut the binding off the book and either rebind the book with a spiral binding or three-hole punch it. Avoid comb binding if possible, since the combs always seem to pop out. If you choose spiral binding, take your newly bound book home to enjoy. If you've had it three-hole punched (as I have), ask for the spine back and get yourself a big enough three-ring binder.
I didn't think to ask for the spine, so made due with an index card. I'll be asking for the spine next time!
Put the front and back covers in the sleeves and the binding in the spine. Load your pages into the book and enjoy the flexibility that comes of being able to remove pages from workbooks while still having a home for them and, best of all, avoid all the sin issues that come from an open book not lying flat!