In The Catholic Homeschool Companion, I wrote about using Saxon math.
I was very meticulous about editing the book, proofreading a hundred times, verifying facts, and researching recommended resources. However, as is true with any nonfiction book, mistakes still slipped through.
My faux pas was in quoting Cathy Duffy on the topic of geometry. You see, Saxon has no separate textbook for geometry. However, if you use Saxon through Algebra 2 and Advanced Mathematics, you will have the equivalent of one full year of Euclidean Geometry. In The Companion, I wrote that if you're uncomfortable with that scenario, you could supplement with Key To Geometry, as recommended by Cathy Duffy. That isn't accurate.
Cathy fortunately caught this and here is what she wrote to me:
I wanted to mention something now before I forget it. On page 21, you say that I recommend using Key to Geometry along with Saxon at high school level. Key to Geometry is really younger level. The program I recommend most is Discovering Geometry, published by Key Curriculum, the same folks who do the Key to series.
It's easy to get them confused. I've occasionally mentioned using Key to Geometry as an introductory supplement for a high schooler if they are really struggling getting the concepts AND if a parent is going to use everything in Saxon and really use Key to Geometry ONLY as a supplement.
My general recommendation is to skip the geometry in Saxon's books, and use Discovering Geometry instead. What you've got on p. 21 reads like it is ONLY a supplement so that's OK as far as it goes, but it should be clear that it is really an option appropriate for younger or struggling students since it's purely conceptual-no mathematical computations involved.
I'll contact the publisher so that future editions can be corrected. Thank you Cathy!