The Gun-Free School Zones Act of 1990 says you cannot carry a firearm onto the property, or within a thousand feet of, a public, private, or parochial school. That statute allows states and certain municipalities to allow individuals, by their own state statute, to go onto a Gun-Free Zone with a firearm.
Colorado allows those with a CCW to go into a Gun-Free Zone, as long as the firearm remains in your vehicle. If you leave your vehicle, for instance to go inside for school business or to pick up your child, you can have your firearm in your vehicle in a Gun-Free Zone, but the car needs to be locked and the firearm needs to be locked inside of a secured container in the car, such as the glove box.
As long as you follow those rules, you are fine carrying a firearm into a Gun-Free Zone. In the interim, if you have any questions about this or anything else, feel free to call my office any time to talk about it.