Children normally start on Phase 2 near the start of their first year at school. This is when most of the letters of the alphabet are introduced. Children learn the letters’ names, and they also learn one common sound for each letter of the alphabet. So for instance, the letter ‘c’ is introduced with a hard ‘c’ sound as in ‘cup’, not the soft sound it has in ‘ice’. And children learn a short sound for each vowel (a, e, i, o and u) – as in ‘hat’, ‘pet’, ‘dip’, ‘pot’ and ‘mug’.
Diphthongs are linguistic elements that fuse two adjacent vowel sounds. English has four common diphthongs. The commonly recognized diphthongs are /aʊ/ as in cow and /ɔɪ/ as in boil. Three of the long vowels are also in fact combinations of two vowel sounds, in other words diphthongs: /aɪ/ as in "I" or mine, /oʊ/ as in no, and /eɪ/ as in bay, which partly accounts for the reason they are considered "long".