It really shouldn't have.
Nationally, the No Child Left Behind Act has dictated that there need to be standards for educational performance, and standardized tests will be used to make sure those standards are met. Although that push started with basics like math and language, national science standards were also called for, and many states have since implemented them; the Kentucky legislature apparently adopted the national standards in 2009. ACT, a company that creates and manages standardized testing, was contracted to handle the science tests.
Given that evolution is extremely well supported and provides the central organizing idea of biology, ACT's tests featured it heavily. That made a number of the state legislators rather unhappy, and gave them the chance to demonstrate that they should not be setting education policy."
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