Eight-year-old Nina brought her report card home from school. Her marks were good - mostly A's and a couple of B's. However, her teacher had written across the bottom: "Nina is a smart little girl, but she has one fault. She talks too much in school. I have an idea I am going to try, which I think may break her of the habit". Nina's dad signed her report card, putting a note on the back: "Please let me know if your idea works on Nina because I would like to try it out on her mother".