Children are taught letter sounds in Reception. This involves thinking about what sound a word starts with, saying the sound out loud and then recognising how that sound is represented by a letter.
The aim is for children to be able to see a letter and then say the sound it represents out loud. This is called decoding.
Some phonics programmes start children off by learning the letters s, a, t, n, i, p first. This is because once they know each of those letter sounds, they can then be arranged into a variety of different words (for example: sat, tip, pin, nip, tan, tin, sip, etc.). While children are learning to say the sounds of letters out loud, they will also begin to learn to write these letters (encoding).
They will be taught where they need to start with each letter and how the letters need to be formed in relation to each other. Letters (or groups of letters) that represent phonemes are called graphemes.