Level 10 - White books are intended to be read with increasing fluency. Children will have learned most of the common letter-sound combinations and can read familiar words automatically without needing to sound out and blend.
Level 11 - Lime books are intended to be read with increasing fluency. Children will have learned most of the common letter-sound combinations and can read familiar words automatically without needing to sound out and blend.
In Level 4 - Blue books, children build on the letter-sound combinations learned in levels 1 and 2. They learn consonant digraphs (sounds made up of two letters together such as 'ch' or 'll') and long vowel sounds (such as 'igh' or 'ai').