We have rats in our school building. Who doesn't?

I always assumed they got into the classroom by squeezing through a slightly open window at night, or under the door from the dank hallway. Their droppings scatter the window sill in the mornings more than occasionally.

But yesterday as I stood in the classroom after school, observing a group of animated, chattering mothers watching over their children finishing incomplete homework, a small piece of light brown trash flew in through the window, landing haphazardly on the floor near the women.

No one seemed to pay any attention, but I had a funny feeling.

As my eyes fell upon the trash fluttering on the floor, it became clear that what had flown in the window was not a piece of trash, but a medium-sized rat.

As it gathered itself from its landing, slowly, then more quickly, it scurried silently across the room and out into the hallway.

I had underestimated our urban companions.