Massive political expenditures by Public Teacher Unions

My own guess is that education vouchers would not only vastly improve the quality of education (improving it the most for those who are stuck in the worst schools, namely where the poor, minorities live), but it would also reduce unionization of teachers and reduce the political pressure that helps hurt the quality of education for those at the bottom of the economic ladder. This discussion explains why you would be missing much of the public unions' political activity if you only looked at their donations to politicians. From the WSJ:

What do the American Ireland Fund, the Rev. Al Sharpton and the Gay, Lesbian and Straight Education Network have in common?

All have received some of the more than $330 million that America's two largest teachers unions spent in the past five years on outside causes, political campaigns, lobbying and issue education.

The contributions—totaling more than $200 million from the National Education Association and more than $130 million from the American Federation of Teachers—were disclosed in annual reports that unions file with the Labor Department detailing their spending on political activities and advocacy work, as well as separate political-action-committee filings. . . .

Members' dues underwrite much of the unions' "political activities," but not donations to candidates, parties and PACs. Those are funded by voluntary contributions. The NEA, the largest teachers union, with about 3.2 million members, also has a super PAC, which can raise unlimited funds. That super PAC had more than $3 million in cash on hand the end of June. . . .