When I had to have my child tested in grade 3 as per our states law requirements, we studied for the test. I tailored my curriculum so he could do well. I sure don't want my curriculum driven by government school standards. Standardized tests cannot measure individualized curriculum. The measure test-taking skills not thinking skills.
Test scores can become the goal rather than the love of learning.
If you must test, homeschool friendly tests such as the PASS Test from Hewitt Homeschooling Resources are less stressful, more accurate and give specifics on how to improve not just scores. The PASS is administered in the home, by the parent. It is un-timed. The level is closely matched to the real achievement level of the student. And the results are normed two ways, with the national population and the homeschool population.