They inevitably are simply scanning or skimming, rather than true reading. Even the average university student actually reads around the same speed, orally and silently. To the contrary, rarely is this so. Only the small number of children with genuine central nervous system dysfunctions experience significant difficulty learning properly taught phonics information. Before Phonics Instruction Is Begun.
Individual letters are the cues all readers use to recognize words.
For example, we know cat and rat are different words because we see that their first letters are not the same. With proper phonics teaching it is justifiable to expect the normal child to reach this state by the end of grade two. More apt pupils can become self-sufficient in reading at even an earlier age. Reading independently means the ability of children to read without help any topic they normally can talk about or otherwise understand. Phonics teaching is de-emphasized and delayed.