I know there are loads of MNers who teach this age group - is it common for a child to get really snagged on one word? He simply cannot get the word "this". He reads it as "the is". However many times I do it with him, explain how the sounds fit together etc, he still just doesn't read it as "this". He can sound out and read more complicated words, like "umbrella", "next" and "mattress", and he can do "the", "there", "than" etc, but "this" gets him every time! I've decided to just treat each time as though we'd never seen it before, keep explaining gently and hope eventually it goes in.
Before people rush in to demand with righteous indignation why I am pushing my 4yo to read - I'm not, I couldn't care less, he doesn't start school till next September anyway, and I wouldn't know how to hothouse a tomato never mind a stroppy 4yo. HE likes reading, he is really into it at the moment. I have got some fuzzbuzz books from a charity shop (we have lods of books, but these are ones he can do virtually unaided, which is exciting for him) and he is racing through them and loving it, but he needs help with some bits.