Don't worry teachers are just as stressed about losing a child etc as you are LOL. Our kindy (prep) teachers stay with the kids at recess for the 1st few weeks and there are always teachers on duty so no one can enter the school without someone seeing. We send all children to the toilet in pairs (my Yr 6s used to tease me about not letting them go by themselves LOL) At all schools I have taught at the big kids look out for the little ones and there are usually so many willing "dobbers" around that no child would get near the gate to run away without the teacher knowing!