Door Knob

Our dog Zoe is a silly animal. When she was small we were training her and found that when she needed to go outside we wouldn't hear her at the door unless we were standing close by. This made for a few messes that we really didn't want to deal with. Then someone told us about putting a bell on the door knob. When she wanted to go out she would ring it (or bat at it). Sure enough within a couple of days she had the hang of it and to this day she will ring her bell when needing to go outside.