Children can be taught up to 461 phonic skills. Most commercial synthetic phonics programmes teach between 90 and 120 skills; the optimal number (that is, the smallest number of skills to read the maximum number of words with minimal confusion) appears to be around 65. For example, three pronunciations are frequently taught for the letter combination ‘ch’ (as in ‘check’ ‘school’ and ‘chef’’), which means that the word ‘chip’ has several phonically plausible pronunciations. In such instances, it is best to focus on just one pronunciation that enables children to read the maximum number of words. The skill-matching within 500 Books is based on the phonic skills that children need to pass the phonic screening test that they take at the end of Year 1. It is anticipated that they will be taught 64 graphemes and 44 phonemes, which generate 85 different phonic skills. Teachers can also match the skills taught through popular programmes such as Jolly Phonics, Letter & Sounds, Reading Write Inc., THRASS as well as Optima Reading.