Are you working hard on test preparation with your middle schoolers or 9th grader? Let me put your mind at ease and make your life a little easier.
I do suggest taking a grade-level, end of the year test, and I'll explain why in a minute.
I do not recommend test prep for younger students for a variety of reasons.
In middle school and early high school, the best test preparation is educating your child in reading, writing, and math. So vocabulary games and workbooks, daily work in math, reading real books - those things all help a child score well on tests.
In middle school and early high school, the best way to prepare for the SAT or ACT test is to give them practice with taking a grade-level test in front of strangers. Taking a grade-level test with a group of homeschoolers is perfect, at that age. They'll get comfortable with filling in bubbles while a timer is going while sitting next to other kids.
Having your child take a simple yearly grade level test can be helpful to a homeschooling parent. It will help you, when you get the scores, so you can guide them in their course selection and college preparation. But taking that test would not mean you have to do test preparation before taking a grade level test. In fact, since it's virtually impossible to get 100% on the SAT or ACT, it's best if they do NOT get 100% on their grade level tests either. You want the child to learn to be calm on a test even when they don't know the answer.
I prefer if parents wait until it's closer to the time to take the SAT or ACT test for real, and then focus on test prep. The exception is if the child has already completed geometry, so that SAT or ACT test prep is appropriate. That's a pretty unusual situation for younger teens.
Grade level tests are nationwide and standardized. They only include very general information on science and history, because not all schools study the same topics, or study them the same way. Now, recently, there is common core to deal with - so I would definitely avoid a test tied to common core if that's possible. If you miss preparing for the test, but are generally doing a good job in homeschooling, a child will not actually get a horrible score. Many homeschoolers know more about history than other school groups because they actually study actual history from a much earlier grade. And many homeschoolers have taken more science in middle school than a 9th grader gets in public school.
In the bigger picture, what does it matter if your child gets a bad score? The score is not reported to anyone, it's not going to be part of the permanent record. The test results are for YOU to see how well your child does. It's for YOU to help with your guidance counselor tasks.
What's the bottom line? You want your child to learn to take a test calmly, whether or not they are being tested on information they don't know and haven't learned yet. Because that's what the SAT and ACT are like. That's actually what LIFE is like, isn't it? We are always being tested on things we don't know about - from installing a computer to trying a new recipe.