The main challenge in this phase is to help children to blend and segment words with adjacent consonants e.g. truck, help. These adjacent consonant phonemes can both be heard when you say the word which makes them different from a digraph where there are two letters that make just one sound. Be careful, lots of people get these confused, including some published materials.
Children with speech and language difficulties can find Phase 4 very tricky. If children struggle to hear all the sounds in a word encourage them to think about the movements that their mouths are making. Looking in mirrors can help with this.
In Phase 4, no new sounds are introduced. The main aim of this phase is to consolidate the children's knowledge, and to help them learn to read and spell words which have adjacent consonants, such as trap, string and milk.