My school district uses the Holt textbooks, 6th grade is 'Holt Mathematics Course 1: Numbers to Algebra', 7th grade math is 'Holt Course 2: Pre-Algebra' and 8th either Holt Algebra I or Transitional Algebra (different publisher) if the student isn't ready for Algebra. My son was a year advanced of that and his class studied from Holt Math Course 1 book in 5th & Holt Course 2: Pre-Algeba in 6th, and Algebra in 7th. Fairly standard for kids in the GATE program.
My guess is that your daughters 6th grade would be the Holt Course 1 book. I wouldn't worry too much about your daughter missing out, as I think this is a book at touches on all expected topics. Elementary Math is often designed to be spiral learning. And that means ever year usually in 4-6th grade, most of the same topics are covered just in more depth every year. My son skipped "4th grade" math with no problems.
