In the context of treatment of specific learning disorders, a particular role is played by the so-called prerequisites. A pre-requisite is a skill or knowledge that helps us develop a new skill or knowledge later. Why is it important to identify a pre-requisite? Because it allows us to work before a skill manifests itself, thus giving us more time and probably more chance of success. Let's think for example of reading: the possibility of working on something other than reading, ma that helps us to enhance the development of reading, allows us to intervene already in kindergarten.
Unfortunately, very often, those that are sold as prerequisites are often "only", from the point of view of research, of predictors. In practice, they are skills that statistically correlate with subsequent skills, and therefore can be used to make assumptions about how a skill will develop or not. Still on the subject of reading, the quick denomination it is considered a good predictor of reading: by looking at children's quick naming skills, I can estimate their subsequent reading ability with good accuracy. However, improving the quick naming may not necessarily improve reading!
In a 2011 article which you can consult freely from here, Purakin and colleagues  tried to identify those skills capable of predict subsequent writing skills as early as kindergarten. In particular they analyzed:
- Knowledge of the alphabet: naming of letters or indicating a word starting with ...
- Metaphonological skills: fusion and syllabic segmentation
- Knowledge of the "meaning" of writing (print knowledge): product brand names, what writing is for, what a newspaper is for, etc.
- Writing your name
- Writing letters
- Writing 3 letter words (CVC like "dog", "cat")
About the writing of the name, the same authors also tried to search a correlation between the length of the child's name and his or her writing ability: In their hypothesis, since children learn to write their own names early, children with longer names might have known more letters, and thus be better at writing. The study, however, did not confirm this hypothesis.
The study found that the two most helpful factors in predicting subsequent writing skills were:
- The knowledge of the "meaning" of writing
- The ability to write letters
It sounds strange, but metaphonology doesn't seem to play such a central role. It may seem counterintuitive, given that writing is certainly done at least by segmenting the word that is transcribed grapheme by grapheme. However, even Italian studies are currently confirming the non-central role of the metaphonological component.