• What year is your child scheduled to take Algebra I?
  • When would you like your student to begin taking the ACT?
The bottom line is that Geometry should be completed (or at least nearly so) before the ACT. Therefore, the one absolute in this equation is that if your student takes Algebra I in the 10th grade, they should take Geometry the following year. For students that take Algebra I before their 10th grade year, the proper order of Algebra II and Geometry should be chosen on the basis of convenience and their target ACT date. 
Further information to be considered:
  • Incorporated into each of these courses is a review of previously learned material. The first several lessons, and sometimes chapters of Algebra II review basic algebraic concepts. Additionally, Algebra is used throughout Geometry, so the concepts are not abandoned for the year if Algebra II does not directly follow Algebra I.
  • To avoid taking Chemistry and Algebra II at the same time is a risky way to set a schedule because, for many students, Geometry is actually more difficult than Algebra II because it is more abstract.
  • Regardless of the order in which these classes are taken, six to eight weeks of review using an ACT test guide (and often a tutor or class) is essential for attaining a desirable score on the ACT.
Soooo... do what works for you:
Take the courses offered at your co-op or tutorial that fits into your schedule. Buy the book at the used homeschool book sale that is cheaper. Teach the same class to your two children at the same time. Most importantly, be at peace.