Protect Schools by Limiting Access

I saw my 6-yr-old grandson on Sunday and couldn't stop looking at him. I was thinking, "20 Ryans?" I couldn't fathom what had happened in Newtown. I have a niece with 2 kids who lives 10 miles away and a nephew with 2
kids 30 miles away.
Giving guns to teachers, principals and custodians isn't going to solve the problem.
Here's my idea: Replace entrance doors at schools with badge/card access mantraps. No card, no entrance. The glass would be ballistic glass, with a supporting structure that is reinforced. If someone who didn't have a
badge tried to get in, they have to show an ID to prove they're on the approved list and answer a challenge question properly.
_Every_ entrance door would be replaced. In _every_ school, not just those in affluent towns.