To better understand this, it's worthwhile considering what aspects of functionality are necessary for any person to cope with daily life.
If I give my child an instruction, such as "Go make your bed", but he doesn't do it - what could be the reasons? Well, he may not want to, that's for sure - making a bed is not necessarily high in his fun priority list. So motivation is key. Maybe he doesn't have the skills to make a bed - it could be as simple as that he may still be quite small, and might find it hard to throw the duvet up high enough to cover the bed. Skills can tie in with his developmental level, or it could tie in with knowledge - does he actually know what steps are involved in making a bed, and in what sequence they go? Being able to place events in a sequence is a developmental skill, with underpinnings in brain pathways we call primitive reflexes. So, early brain development and knowledge (task-analysis) is also key to functionality. Or, maybe he's feeling poorly or really hungry, and just not up to making his bed - he'd rather crawl back into it. So his biochemical and metabolic state is also crucial for functionality.
If we have to summarize the factors that are crucial for functionality in children (or in adults, for that matter), we could group them into three major categories:
- Behavioral - which includes skill and motivation
- Developmental - which includes brain development and activity, the maturity of certain hard-wired nerve pathways called reflexes, and the level of development of various sensory systems
- Biomedical - which includes things that are in his system that are hampering his brain function, or things that are lacking in his system, that makes it harder for his brain to function.
