Point to a sound and say it together, then the picture word: βsh, shipβ. Say the sound, not the letterβs name, and keep it short: βmmmβ, not βmuhβ.
When your child is writing and gets stuck on a sound, ask them to find it on the mat rather than telling them. Looking it up is how the spelling sticks.
Each mat has the sounds of one phase, in the order Letters and Sounds teaches them, which most schools in England follow or something close to it. Phase 4 adds no new sounds: children blend the ones they know into longer words, like frog and tent.