Physical Danger
Insert joke comparing schools to prisons. Applause sign. Everybody clap.
The truth is, unfortunately, a lot less of a joking matter. Since many educational psychologists will be acting as school counselors (or otherwise working in a grade school environment), they will be tasked with working with those students most prone to acting out. This can mean the occasional violent outburst, either directed at you, another student, or faculty member.
It kind of comes with the territory. School is an emotional time for everyone, and each growing adolescent will develop in their own way. Trust that you will have the tools necessary for dealing with these problems: communication, empathy, and authority, not hockey pads and facemasks.
Most days, work won't be any more dangerous than an overly excited preteen dropping a textbook on your foot. Other days might involve a misplaced stapler being chucked at your head. You really just never know what the day will bring, just be prepared for anything (and practice ducking).