DD is nearly 2y 6m. We do a Diddi Dance class once a week. She apparently loves it - can't wait to go and often talks about it in the week, or did at first.
When she first went with the CM she didn't do lots of the class but gradually joined in more and more. Now I am on maternity leave and take her she will almost not join in at all, except if it is with me. It's not that I mind too much, but I am often the only adult (most are childminders or nannies) taking part, and it makes me wonder if I should do something different to encourage her to take part alone - or even stop the class.
She is pretty independent and sociable in other ways - though this is the only "class" she goes to.