As many as 20 states have considered enacting parent trigger laws, which would let parents who are dissatisfied with the way a school is being run, turn it into a charter, replace the staff, or even shut it down, if 51 percent of the school’s families agree. The laws — which have been passed in various forms in California, Connecticut, Mississippi and Texas — have generated controversy and even inspired a movie to be released this fall. Do these laws give parents the first real power over their children’s education? Or do they put public schools in private hands and impede real improvements?