Having problems pronouncing the word 'S'?

My friend had this problem. She went to a doctor and he made her do "weights" with her tongue. WHat she did was attach some marble like tings on a string and then hold it in between her teeth. Then she had to lift the string up all the way into her mouth trying to use her tongue. Does this make sense? She also put some ruber bands (the braces type) in her mouth and was told to talk with them. It made her pay more attention to how she was forming words so she wouldn't swallow the rubber bands