The spend-down has begun. If you live in one of Colorado’s hotly contested school districts, you have probably noticed by now. The banner ads attached to web pages like this one. The commercials inserted into your Facebook feed. The glossy 8x11s filling your mailbox with virtue and venom, some brightly colored and peppy, others black and gray with yellow text. After months of raising money, school board races are now in the few short weeks of spending it.