Description Collecton 1 books are designed for early readers ready to apply the letters and sounds they know to enjoyable texts. The earliest books in the set include VC and CVC words with short vowels a and i, then gradually add o, e and u. Later, the books also include suffix -s, the digraphs sh, th, wh and ck and double letters. High frequency words are introduced across the series to provide children wider access to text.