Sally's report card

Eight year old Sally 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:
"Sally 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."

Sally's dad signed her report card, putting a note on the back: "Please let me know if your idea works on Sally because I would like to try it out on her mother."