A grapheme is a spelling of a sound. It can be a single letter (the b in bat), two letters (the ch in chip), three letters (the igh in fight), and even four letters (the ough in thought). So, how many graphemes are there? I would guess the number to be around 160 to 180 if you require a grapheme to appear in at least three unrelated words. Two occurrences or less and it's just an odd spelling.
How Many Graphemes Should Be Taught?
This is a better question. This website has published The OnTrack Reading Phonogram Flash Card Set which has 84 graphemes that are common enough to definitely warrant teaching. But that set was purposely limited because it was devised as part of an adaptation of the popular Spalding Method.
Neither Spalding nor the OnTrack Reading flash cards included either doubled consonants like bb, dd, tt, etc., or split vowels like a-e, i-e, or o-e. That's another 17 graphemes in all, although teaching the twelve doubled consonants is a trivial exercise (same sound as the single consonant) and so they probably don't need to be included in a list to be explicitly taught.
Here are the ones that I think need to be added to the OnTrack Reading flash cards to produce a good teaching set of one hundred graphemes:
- a-e (made)
- e-e (eve)
- i-e (pine)
- o-e (tone)
- u-e (cute/tune)
- augh (caught)
- te (route)
- dg (badger)
- gh (ghost)
- mn (hymn)
- mb (comb)
- sc (scent)
- st (hustle)
- ugh (laugh)
- the (soothe)
- gue (league)
And, yes, there are more. The ending digraph pe that we find in coupe and cantaloupe, or the digraph ye in bye and dye, or the digraph lk in talk, walk, and chalk, to list three examples. But these, and others as they are encountered, can be used to illustrate to a student that he will continue to encounter an occasional new grapheme as his reading vocabulary increases throughout his schooling.
Below, you can download a list of 100 graphemes that occur often enough in early reading that they should be explicitly taught, along with the sounds that should be explicitly associated with each one.
As the note on the list states, sixty-nine of the 100 graphemes have only one associated sound. Put another way, 69% of the phonics code that should be explicitly taught consists of just one-sound to one-grapheme relationships.
The English phonics code is admittedly messy, but that just means that the way we teach it has to be well-organized. And a significant part of that organizational process is what graphemes should be explicitly taught to young readers. This list of 100 graphemes seems a good start. It's very close to the phonics code taught in the OnTrack Reading Phonics Program, for example.