As l wrote in the previous post, when children are writing an unknown word, one of the ways of solving it is to stretch it out to hear the parts. In Reading Recovery we use sound (Elkonin) boxes to say the words slowly in order to hear the sounds and then choose a letter or letters to represent each sound. Once the student has mastered this he / she begins to use letter boxes.
The focus goes from What can you hear? to What would you expect to see?
The more we read, the more our eyes are used to looking through words and the more we expect to see repeated letter combinations. In English we do not expect to see letter combinations within words such as wxlq. We do expect to see combinations such as ing, er, ch, ea, oa, sh, ck, ee.
If the student is using letter boxes, the teacher would draw 4 boxes because there are 4 letters in duck. The student is required to think about what letter is likely to go in each box based on what the word is likely to look like.