To some extent, a curriculum's worth can be judged by how easy it is to describe—for homeschool moms trying to cram every subject and the housework into a single day, easiest is often best. While unit studies often claim to make things easier on harried mothers by teaching multiple subjects across a potentially broad age-spectrum, those who've tried to implement them know they usually aren't as simple as their authors suggest.
America the Beautiful by Charlene Notgrass is an exception. While not technically a unit study, this U.S. history course for grades 5-8 puts the best elements of interdisciplinary study in a textbook context. There's no need to hunt down all kinds of supplementary books (most likely out of print or really hard to find) because everything you need comes in the curriculum package, but at the same time you're free to tailor content to each student.
America the Beautiful is a one-year course for middle school students built around a two-volume core textbook/teacher's guide/reference manual. Each volume includes 15 units of five lessons each, for a total of 75 lessons per semester (150 altogether). Lessons are usually 2-5 pages, and include text to read, assignments linking the other books in the program, and hands-on activities. Students can either read the lessons on their own or have them read aloud by parents, depending on your child's primary learning mode (auditory or visual).
Units are arranged by time period and most include one lesson devoted to American history, one biography, a Daily Life sketch, a lesson on an American landmark (manmade), and a lesson on an element of God's creation relating to the time period. At the end of each lesson is a list of activities for students to complete, including Thinking Biblically, creative writing and vocabulary assignments, literature reading (ten works of fiction are assigned), timeline and map exercises, and assignments in one of the two student workbooks available; a single family activity is assigned per week (a recipe, craft project, etc.).
The two main volumes are the central elements, but there are six supplemental books. Timeline of America the Beautiful and Maps of America the Beautiful include a timeline and maps respectively (surprise!) that students complete as per the corresponding lesson assignment. We the People contains source documents from America's history including speeches, songs and poems, excerpts from longer works, even copy from old-timey ads (very cool).
A Student Workbook includes crossword puzzles, word searches, etc., and is recommended for grades 5-6; a Lesson Review book for grades 7-8 reinforces lesson content with quizzes, short answer questions, and more. While you could have students work through both texts (assignments in both are short, generally less than half a page), the authors encourage you to use one or the other for each student. The Answer Key includes answers for all written assignments in the consumable workbooks and the main texts.
In keeping with the unit study theme, ten novels are assigned in addition to the textbook reading. All of them are classics of young adult literature (The Sign of the Beaver, Little Town on the Prairie, Across Five Aprils, etc.), except the novel Katy, by one of the Notgrass' daughters, about a Christian homeschool family. While these add a "fun" element, the main texts are pretty fun on their own—Charlene Notgrass writes concisely for middle school kids without dumbing anything down, and both volumes are profusely illustrated with color and black and white photographs and artwork.
The student is given 1-2 weeks to read each book, with 1-3 chapters assigned each day.
Sometimes a curriculum bites off way more than it can chew. On first glance (if for no other reason than the profusion of workbooks and the long lists of activities) it would seem the same could be said of America the Beautiful. Yet it really does offer what it claims—it's a unit study-ish approach to history from a Christian perspective that is genuinely easy to implement. Teachers won't have to spend tons of time preparing lessons, and kids will enjoy learning U.S. history and geography.
The Christian perspective is clear throughout, but it doesn't lead the authors into common mistakes—either Christianizing historical figures who weren't, or vilifying others unnecessarily. Kids will get a good sense of the flow of the American narrative from the Viking explorers to the present without getting bogged down in names and dates. Much of what is covered here is covered in the Notgrass Exploring America curriculum for high school students, though America the Beautiful focuses on individuals while Exploring America covers events more in-depth and offers more Christian evaluation. If you want a good foundation for your mid-age students, this is an excellent choice.