I've just come from a playgroup where my 21mo DS refused to sit down and join in both snack time (fruit) or sing song time. He wanted to play with the cars and 2 very fancy garages they have there. I just assumed he wasn't hungry/interested. Saying that, his dad isnt exactly what you'd call a "joiner in-er"!
I wouldn't worry about this too much, Ive worked at many nurseries and have a boy who has just turned 3. Their attention span is not that great at this age and if the stories are not made interesting enough for him, he will find it harder to engage and concentrate. Every child is different and maybe the teachers need to home in on his needs a bit more, maybe he prefers more hands on learning like props with the story so that he can engage, or maybe he needs to be up at the front so he can see and hear clearly. Sometimes one to one stories or in a smaller group may also help. If it does not improve, many you could suggest a few of these points to them. Hope this helps
My Ds turned two in NOvember. From what I see and understand he doesn't sit still during nursery circle time. He goes three times a week. He either sits apart on or the edge and starts to roam around or do his own thing. They say he has got a bit better but this morning when I dropped him off (a bit later so story reading had started) he sat at a table while the story was being read.
When is this a problem? He's got a poor attention span and on the go a lot; likes to play with people. But he's also a great sleeper and loves one to one quiet time.