I kept a female chessy pup for a friend. She was 7 wks when I picked her up and almost 12 when he got her. I found her extremely frustrating to house break. I would put her out and she would come right in the house and pee. It was as you mentioned she would get playing and exploring and forget why she was outside. If I stayed right with her and kept reminding her to get busy she was fine. I think the problem is now solved.