my child has 4 years he didn't sit on his seat at school is this any serious

A. Hello good evening !! Yes toddlers do ,due to new to the environment they may not sit attentively ,some might cry ,while some might play around . But over the period by 1-2 weeks they set to the atmosphere . But if the teacher or you observe any red flags like less attentive,no direct eye contact,not mingling with kids ,frequently moving not sitting at one place while playing or in activities then might be concentrate issues,hyper activeness need to consult Developmental Paediatrician.