Regardless of what your friends say, and since testing isn't required in Frederick County, the choice is completely up to you.
Some homeschool parents need milestones to track how their kids are doing, so achievement tests can offer that overall picture of progress. The results from achievement tests will show strengths and weaknesses as reflected in a typical curriculum taught for a specific grade. Especially for middle school and high school age kids, these kinds of tests provide an opportunity to practice "test taking skills" which can be an advantage if they plan to take the GED, college entrance exams, and placement tests.
Conversely, if your kids are progressing to your satisfaction, the need to take an achievement test wouldn't necessarily be high on your list. And, many homeschool parents don't feel it necessary if their kids are achieving certain educational milestones.
