Who Decides What Our Kids Will Learn: Where do Standards Come From?

In the last decade, we've heard a lot about standards, specifically Common Core standards and how they are "rigorous".  Who are the people who decided what your kids would learn?  How should we decide what standards are "rigorous"?  Should money be the driving factor? What if they've never been tried before?  Should we experiment on an entire generation of school kids?  We did!