I found these by accident. A link, or something, that led me to the Teachers Pay Teachers site, which BTW, has some good stuff. Not all of it is great, but some of it has been helpful to me.
The premise behind the workbook series is that if you get kids creating art, math happens naturally. And it does.
There are two workbooks that aren't really necessary, in my opinion. One is called Native American Geometry Workbook, and in the corner it says "Student Files." Although it is interesting to read through and see the work students have produced, it isn't essential.
The other is called Native American Geometry Workbook Series "Howdy," w/ printables.
This one is 33 pages, and though it has great information in it, it is pretty much a retelling of what is in the student files workbook.
When I got these they were both free.
I paid for Volume I, which is 159 pages, Volume 2.1, which is 70 pages, and Vol. II: 2, which is 116 pages. These seem like a great way to introduce Geometry while making it apply to everyday life.
I like the Montessori materials, and the way the information is presented, but especially at the adolescent plane I think it is important to show how it is meaningful to our lives. We are using Keys of the Universe Geometry Album alongside this series.
These workbooks start with having the student produce beautiful artwork, and progress to Pythagorean demonstrations through gardening.
As I presented the first lesson Sean was eager to begin. I can't wait to see how this progresses!
Here's a link to Vol. I.
If you've already used these, I'd love to have your feedback in the comments!