I often hear of similar problems, 'Want an Orange'. I have coached numerous 5-7 year olds and the most common problem that stops them achieving well in Literacy is the fact that they don't understand what they are supposed to listen to in words (phonological awareness) when the lessons pass the 3 letter word stage, such as 'cat' and 'dog'. They can often remember these words visually because they are short words and they have seen them before.
To be able to spell and write well they need to be able to hear the phonemes (sounds) in words. After they have learnt to do that they need to be able to match them to the graphemes (letters).
What tends to happen is that the children learn all the 'letter sounds' before they learn to listen to words and work out the sounds in them. This makes them concentrate visually on the letters. They are learning the process back to front.
The children then become confused and then unable to segment (split up) the sounds in words in a word such as 'help': the most usual mistake is spelling it 'hep'. Most children can't hear the 'L'. If they have SEEN the word before they sometimes spell it as 'hlpe'. They recall the letters, but don't attempt to listen to the word to hear the order of the letters, except, perhaps for the first and last letters.
These children need to be taught how to match the phonemes they hear to the graphemes they need to write. If the teachers aren't doing that it is because they may not have been trained to do it that way.
Ask the teacher how good your child's phonological processing skills are.
He should be able to recognise the word 'stand'
when you SAY the PHONEMES s- t -a -n -d
(actually when we say the word 'stand' it sounds more like 'sdand', because it is difficult to hear the t distinctly after the s),
so if he can't make the word try saying s- d- a- n- d for him to listen to.
DON'T show him the graphemes.
Ask him if he can say the sounds in a word such as 'brand'
Ask him if he can say the word 'brand' without r. It will be 'band'.
If he can do all of those things, then his phonological processing is OK. It may be something else that is holding him back.
His teacher needs to do a similar test with him to discover what can be done to help him. The teacher should have a bank of tests like this to use.
If you have any more questions about phonics post them here:-)