Grapheme:

A grapheme is a letter or a number of letters that represent a sound (phoneme) in a word. Another way to explain it is to say that a grapheme is a letter or letters that spell a sound in a word.

Phoneme:

A phoneme is the smallest unit of sound in speech. When we teach reading, we teach children which letters represent those sounds. These can be single letters, two letters making a digraph or three letters making a trigraph.

Digraph:

A digraph is a phoneme (single sound) that is made up of two letters. A vowel digraph is made up of two vowels making a new sound for example o and a making /oa/ as in goat. A consonant digraph is made up of two consonants making a new sound, for example c and h making /ch/ as in chip.

These are not to be confused with consonant clusters, these are two consonants together that do not alter the phoneme, for example b and l are /bl/, the phonemes have not changed. These are taught in Phase 4 of letters and sounds.

Trigraph: 

A digraph is a phoneme (single sound) that is made up of three letters. For example, a, i and r make up the phoneme /air/ as in hair.

Segment:

Segmenting in phonics is the ability to separate a word into its sounds. To spell out the word ‘cat’, for example, you would segment it into each of the sounds the letters make: c - a - t. Segmenting the word into these phonemes helps children work out what graphemes to use to write that word out.

Blend:

Blending is a method used to help children learn to read by combining sounds to make a word.  When beginning to read, children will say each phoneme aloud and then try say the whole word. For example, c-a-t, cat or p-i-g, pig. When a child becomes more confident with reading, they become fluent.

Fluent:

The ability to read without having to segment and blend words. Children will eventually learn to recognise words by sight as adults do. Children should also understand what they are reading if they are fluent. They should be able to discuss what they have read with confidence. This is the ultimate goal when teaching reading.