My nearly 9-year-old daughter uses "f" and "v" sounds for words with a "th" sound in, eg if saying the word "thought" she would pronounce it "fought"; if saying the word "than" she would pronounce it "van". I don't know whether she is likely to simply self-correct given time, or whether we should be trying to get her referred for speech therapy. I am also not sure to what extent we should seek to correct her - I don't want her to get the feeling that every time she speaks her parents are going to leap in and correct her pronunciation rather than listen to what she has to say. Would welcome advice on this.