Three students -- two 17-year-olds and a 16-year-old -- were shot and wounded Wednesday near a Pittsburgh high school as they walked to their car after classes. A 20-year-old man armed with an AK-47-style rifle and 500 rounds of ammunition entered an elementary school in Decatur, Ga., on Aug. 20 and fired a few rounds but surrendered before anyone was injured. A 45-year-old teacher was shot to death, allegedly by a 12-year-old student, at Nevada's Sparks Middle School on Oct. 21. The next day, a Massachusetts high school math teacher was stabbed to death with a box cutter, allegedly by a 14-year-old student.

It'd be easy to conclude that school has never been a more dangerous place, but for the USA's 55 million K-12 students and 3.7 million teachers, statistics tell another story: Despite two decades of high-profile shootings, school increasingly has become a safer place.

The trend is playing out against a backdrop of jitters over school security that have accumulated since Newtown. Schools in some states are urged to issue concealed handgun permits to teachers and buy them bulletproof whiteboards and desk calendars. An Ohio company sells a $100 Kevlar insert it says will make any backpack bulletproof. Educators attend training sessions in which they're advised to charge armed attackers.