Dozens of schools are shot up wry [every] year in the u.s.
Citation needed; AFAIK, that actually only happens once every decade or so, it's not the norm by any measure.
Wikipedia lists 14 school shootings so far this year.
In the last 12 months, 7 incidents where people died:
September 26, 2012 Stillwater, Oklahoma (suicide)
December 14, 2012 Newtown, Connecticut (major news incident, highest number of deaths since 2007)
January 15, 2013 Hazard, Kentucky (college parking lot)
January 16, 2013 Chicago, Illinois (university parking lot)
January 29, 2013 Midland City, Alabama (ok, a school bus, not a school)
March 18, 2013 Orlando, Florida (university, killer was ready but changed his mind, suicide)
June 7, 2013 Santa Monica, California (college)
Even if you just limit it to "major" events with 5+ homicides
Red Lake massacre, 2005
Amish school shooting, 2006
Virginia Tech massacre, 2007
Northern Illinois University shooting, 2008
Oikos University shooting, 2012
Newtown, 2012
Santa Monica shooting, 2013
7 in the last 8 years.