Just thought of another favorite thing we did that would be fun - especially with the new movie coming out soon. It's more of an activity, though...
I gave each kiddo (and myself!) a dragon described in the Fantastic Beasts and Where to Find Them book and they had to draw a very detailed dragon according to the description in the book. Sort of following the style of the Dragonology books (we labeled things, wrote little descriptions in the corners, wrote fancy-lettered titles at the top of each page w the name of the dragon...):
http://static.srcdn.com/slir/w570-h337-q90-c570:337/wp-content/uploads/Interior-Page-from-Dragonology-Book.jpg
http://vignette4.wikia.nocookie.net/ology/images/c/c2/076362814X_int_1.jpg/revision/latest?cb=20080723145633
We spent about 30 minutes per dragon/beast assigned and sat down a few times a week to draw. The rules were: If the book described something in detail, we HAD To include it in the drawing-exactly as described. If it didn't give specific details (ie. color, size, etc) we were allowed artistic liberties. My youngest was probably your kids' age when we did this.
We did them on blank sheets of paper, and when we'd completed all of them we found interesting, I bound them together. It's one of my favorite things to stumble across when I go through the shelves. :)