Description Temin has found talking socks! However, they only seem to say ow and oi. Do the socks say anything else? And who do the socks really belong to? The phonemes /ow/oi/ are featured in this title. 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').