As y'all may know, I am very much in love with giving the boys extra school work at home. We spent all last school year and this past summer working on Singapore Math*, and recently added books from the Critical Thinking series (the link is to Two's book. One has book E). Here are a few more books I've found that are interesting as add-ons to their school experience. Please feel free to let me know if you have information about any of them; aside from the Jacob's Ladder book, they're all in my Amazon shopping cart, waiting for me to sell enough no-longer-read books to make the purchase of new things palatable.
Jacob's Ladder Reading Comprehension Program, Level 1: This is for Two, who isn't the reader his brother was at this age. I've also heard from some parents who have been at our school longer than we have that the children sometimes struggle with reading comprehension. This has never been an issue for us before, as One did an SRA a day for two years at Montessori. I want to make sure Two is well-prepared in reading comp, so this is what we've chosen. It's one of the many excellent resources created and/or recommended by the Center for Gifted Education at The College of William and Mary.
The Wallchart of World History: Amazon doesn't have a picture of this, but you really should check out Ann Voskamp's post on it (and on many, many other home schooling treasures). It looks like it will keep One busy for days, if not years.
Writing Mysteries in the Classroom: As fantastic a reader as One is, he is a little bit scared about learning to write. I thought this might help take some of the pressure off, by giving him something fun to create while he was learning. I guess I'll find out if that's true, won't I?
Math-a-logic: This is for One, when he needs a change from Singapore. It blends math with logic concepts such as Venn diagrams and analogies, and sounds like an interesting break from fraction division.
Spatial Reasoning A Mathematics Unit for High-Ability Learners in Grades 2–4: This is for Two, the most tactile learner in town. It requires the purchase of several sets of manipulatives, though, so I may be waiting a bit. Although I have located said hard-to-find materials here, here and here. As the title suggests, this is something we can work on for a while, which makes me think it will be worth all the extra flapdoodle.
* a note or two on Singapore Math. These books are from the official website (that I linked to above) and are the best I've found. You can also purchase them at Sonlight, an excellent source for home school (and extra school) materials. I don't buy the textbooks or teacher's editions - just the workbooks - as the math is fairly self-explanatory. Frequently the boys go days without asking for my help on any assigned pages. The best thing to do before starting the program is to have your child take a placement test. Singapore tends to be ahead of other curriculums (such as Everyday Math, which the boys use at school) and you want to start at the right level. I can't say enough good things about these books: they provide a traditional approach to math instruction (something new, then review, drill, drill, drill); I've not found their equal elsewhere.