Most children are already competent users of their native language by the time they go to school, and reading develops from this foundation. Indeed as Mattingly (1972) proposed more than 30 years ago, "reading is parasitic on speech." However, learning to read is not a straightforward matter because, at a minimum, it involves breaking a code that maps spoken on to written language. How difficult it is to break the code, and how much else there is to learn before reaching an adult level of proficiency will depend upon a wide range of factors, some intrinsic and others extrinsic the child. These are themes that recur in different chapters in Part III.
Byrne makes clear that reading is the product of the learner and the environment, so in this view what needs to be taught is what the child does not bring to the learning situation. He proposes that one of the reasons that learning to read is difficult is that children start out with incorrect hypotheses about what print represents; in short they think that the symbols map to morphemes rather than to phonemes and, for children learning to read in an alphabetic language, this can lead them astray. Failures of learning are discouraging, and a failure to understand the alphabetic principle (that graphemes map onto phonemes) represents just one point at which children can become discouraged about the reading enterprise. Even with alphabetic insight the child must acquire knowledge of all of the letter sounds, must understand that not all features of the sound stream are represented in the orthography and must also learn that there are one-to-many and manyto-one correspondences.
Treiman and Kessler's consideration of the process of learning to spell and their review of writing systems raises some very similar issues to those discussed by Byrne. In all writing systems, a key issue for children is to work out what the system they are learning represents and, on the other side of the coin, what it ignores. In general, writing systems ignore suprasegmental (e.g., intonation and stress) features of speech, and they do not convey information about regional dialect. What they represent depends on the system in question.