She sounds to me like a lot of the children I work with at KS3! In your judgement do you think that she is unable to sound out and blend words because she doesn't know the letter/sound correspondences (for example, if you showed her 'ea' would she be able to tell you that it could be /ee/ , sea, /ai/, great or /e/, head?) or because she hasn't been required to to it in the past and is lacking in practice? If it is the first she will need do to some work on learning the correspondences that she doesn't know and using them to sound out and blend words, starting with single syllables and working up to multi-syllables (you may have to use nonsense words if she can 'sight read' most of the single syllable words) If it is the second she will need lots of practice, once again, starting simple and moving to complex. She may well be accustomed to being 'told' words she doesn't know. Don't do it! She has to work them out herself. I, personally, have not yet encountered a child who cannot blend at all (though I am always open to the idea that I might in the future), but if it is not their habitual strategy it takes quite a long time to break the 'guessing' or 'skipping' habit; both of these strategies are much easier and children can slip back into them if not closely monitored.