Anyone who takes an objective look at English spelling can easily understand why phonics is useful only in the early stages of learning to read, with words that entirely decodable.
The final aim of reading instruction is to be able to read all common words by sight instantly, as everyone on this forum can. With regularly spelt words of the 'fat cat sat' variety children can get to that stage by simply improving their decoding speed. With the trickier ones (like 'one'), most children keep getting repeatedly stuck and need a great deal of patient help, although some manage to work them out for themselves, utilising their context.
The ORT books were written mainly for the purpose of teaching the trickier words, such 'once, only, other'. They become far more manageable for children if parents or teachers pick out the tricky words in then and go over them a few times before asking children to read one of the books.
In all there are around 2000 common English words which are not entirely decodable (see Sightwords on my website if interested), but as children's vocabulary and mastery of grammar grows, they become better able to access most of them. The tricky words which most deserve teaching, after basic phonics, are the most HF ones.
In the first 100 most used English words, the following 41 contain some tricky or surplus letters:
the, he, be, we, me, she,
of, to, was, want, all, call, one, said,
you, by, my, only, come, could, do, down, into, look, now, other, right, some, there, two, when, what, where, which, who, your,
are, have, before, more, were.
In the next 200 these are tricky in some way:
another, any, many, saw, water, small, laughed,
bear, great, head, ready,
(ever, never,) every, eyes,
find, friends, giant, I?ll, I?m, key, live, river,
people, pulled, put, thought, through, were, work, would,
coming, everyone, gone,
most, mother, oh, once,
grow, how, know, snow, town, window,
book, food, good, room, school, soon, too, took, door,
Mr Mrs magic,
(and depending on accent)
after, asked, can?t, fast, last, plants.
Once children have mastered basic phonics and can read all the above, the ORT books become easy.
Masha Bell