my dd is not like that at all, although she'll have an activity she'll want to do ad nauseum, at the moment its writing cards, this has been going on for months..... Mummy I need to make a card for someone - every day.

Before that it was wrapping presents which lasted about a year. I think these are more like schemas though. At any rate I'm sure she gets something out of it.

I think the obsessions are like that too. Not only are they attempting to master a particular idea but they are using the idea to learn about other things which might not be easily related. eg the number 5 can be a gateway can be a gateway for exteneding knowledge on time, space, shape, relationships etc. I think sometimes these kids just have awesome ways of connecting ideas and are getting soooo much more out of things than we know. just an idea...