Fortunately, schools are very secure these days.  Way more secure than when I was a kid.  To get into most schools, you need to show ID, sign in, and (sometimes) wear a visitor badge for the duration of your visit.  If you want to pick your kid up, there are even more security precautions.

But, how do you keep your kids safe from abduction when they're away from you and school?

Give them a password!  Something easy to remember, but difficult for someone to guess.

If a stranger, or someone they do not know that well (yes, unfortunately, abductions by family friends do happen) tries to pick them up, have your kids ask for the password.  If the adult does not have the password, the kids are to call for help.  Just that simple.

Some people who have used this method say that their kids simply asking for the password has caused potential abductors to flee.