it may not seem like much, but lets say one officer for every school for an 8 hour shift for 150 days is 1200 man hours per year per school. There are approximately 118 public schools in Columbus alone. Now were are at 141,600 additional man hours just for being at the school. That does not include the time before/after, expenses going to and from, and insurance cost for more staff.
May not seem like much upfront, but our country is in enough debt as is. Arming teaching is a quick/easy solution while the social issues are address.